Risk of Breast Cancer After Diabetes in Pregnancy: A Population-based Cohort Study

OBJECTIVES

Diabetes is associated with an increased risk of several cancers, including postmenopausal breast cancer. The evidence for higher breast cancer risk after diabetes in pregnancy is conflicting. We compared the incidence of breast and other cancers between pregnant women with and without diabetes.

METHODS

This work was a propensity-matched, retrospective cohort study using population-based health-care databases from Ontario, Canada. Those deliveries with gestational diabetes mellitus (GDM) and pregestational diabetes mellitus (pregestational DM) were identified and matched to deliveries without diabetes mellitus (non-DM). Deliveries from each diabetes cohort were matched 1:2 on age, parity, year of delivery, and propensity score to non-DM deliveries. Matched subjects were followed from delivery for incidence of breast cancer as a primary outcome, and other site-specific cancers as secondary outcomes. We performed Cox proportional hazards regression to compare rates of breast cancer between matched groups.

RESULTS

Over a median of 8 (interquartile range 4 to 13) years of follow-up, compared with non-DM deliveries, the incidence of breast cancer was significantly lower for GDM but similar for pregestational DM deliveries (hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.82 to 0.98; and HR 0.92, 95% CI 0.80 to 1.07, respectively). GDM was associated with a significantly higher incidence of pancreatic and hepatocellular cancer, and pregestational DM was associated with a higher incidence of thyroid, hepatocellular, and endometrial cancers.

CONCLUSIONS

Diabetes in pregnancy does not have a higher short-term risk of subsequent breast cancer, but there may be a higher incidence of other cancers.

Association of a calcium channel blocker and diuretic prescribing cascade with adverse events: A population-based cohort study

BACKGROUND

Prescribing cascades occur when a drug adverse event is misinterpreted as a new medical condition and a second, potentially unnecessary drug, is prescribed to treat the adverse event. The population-level consequences of prescribing cascades remain unknown.

METHODS

This population-based cohort study used linked health administrative databases in Ontario, Canada. The study included community-dwelling adults, 66 years of age or older with hypertension and no history of heart failure (HF) or diuretic use in the prior year, newly dispensed a calcium channel blocker (CCB). Individuals subsequently dispensed a diuretic within 90 days of incident CCB dispensing were classified as the prescribing cascade group, and compared to those not dispensed a diuretic, classified as the non-prescribing cascade group. Those with and without a prescribing cascade were matched one-to-one on the propensity score and sex. The primary outcome was a serious adverse event (SAE), which was the composite of emergency room visits and hospitalizations in the 90-day follow-up period. We estimated hazard ratios (HRs) with 95% confidence intervals (CI) for SAE using an Andersen-Gill recurrent events regression model.

RESULTS

Among 39,347 older adults with hypertension and no history of HF who were newly dispensed a CCB, 1881 (4.8%) had a new diuretic dispensed within 90 days after CCB initiation. Compared to the non-prescribing cascade group, those in the prescribing cascade group had higher rates of SAEs (HR: 1.21, 95% CI: 1.02-1.43).

CONCLUSIONS

The CCB-diuretic prescribing cascade was associated with an increased rate of SAEs, suggesting harm beyond prescribing a second drug therapy. Our study raises awareness of the downstream impact of the CCB-diuretic prescribing cascade at a population level and provides an opportunity for clinicians who identify this prescribing cascade to review their patients' medications to determine if they can be optimized.

Physical Activity During Adolescence and Early-adulthood and Ovarian Cancer Among Women with a BRCA1 or BRCA2 Mutation

In the general population, physical activity has been associated with a lower risk of several cancers; however, the evidence for ovarian cancer is not clear. It is suggested that early-life physical activity may differentially impact risk. Whether this is true among women at high risk due to a pathogenic variant (mutation) in the BRCA1 or BRCA2 genes has not been evaluated. Thus, we performed a matched case-control study to evaluate the association between adolescent and early-adulthood physical activity and ovarian cancer. BRCA mutation carriers who completed a research questionnaire on various exposures and incident disease and with data available on physical activity were eligible for inclusion. Self-reported activity at ages 12-13, 14-17, 18-22, 23-29, and 30-34 was used to calculate the average metabolic equivalent of task (MET)-hours/week for moderate, vigorous, and total physical activity during adolescence (ages 12-17) and early-adulthood (ages 18-34). Conditional logistic regression was used to estimate the OR and 95% confidence intervals (CI) of invasive ovarian cancer associated with physical activity. This study included 215 matched pairs (mean age = 57.3). There was no association between total physical activity during adolescence (ORhigh vs. low = 0.91; 95% CI: 0.61-1.36; Ptrend = 0.85), early-adulthood (ORhigh vs. low = 0.78; 95% CI: 0.51-1.20; Ptrend = 0.38) and overall (ORhigh vs. low = 0.81; 95% CI: 0.54-1.23; Ptrend = 0.56) and ovarian cancer. Findings were similar for moderate (Ptrend ≥ 0.25) and vigorous (Ptrend ≥ 0.57) activity. These findings do not provide evidence for an association between early-life physical activity and BRCA-ovarian cancer; however, physical activity should continue to be encouraged to promote overall health.

SIGNIFICANCE

In this matched case-control study, we observed no association between physical activity during adolescence or early-adulthood and subsequent risk of ovarian cancer. These findings do not provide evidence for an association between early-life physical activity and BRCA-ovarian cancer; however, being active remains important to promote overall health and well-being.

Survival of Filipino women with breast cancer in the United States

BACKGROUND

The survival of women with early-stage breast cancer varies by racial group. Filipino women with breast cancer are an understudied group and are often combined with other Asian groups. We compared clinical presentations and survival rates for Filipino and White women with breast cancer diagnosed in the United States.

METHODS

We conducted a retrospective cohort study of women with breast cancer diagnosed between 2004 and 2015 in the SEER18 registries database. We compared crude survival between Filipino and White women. We then calculated adjusted hazard ratios (HR) in a propensity-matched design using the Cox proportional hazards model.

RESULTS

There were 10,834 Filipino (2.5%) and 414,618 White women (97.5%) with Stage I-IV breast cancer in the SEER database. The mean age at diagnosis was 57.5 years for Filipino women and 60.8 years for White women (p < 0.0001). Filipino women had more high-grade and larger tumors than White women and were more likely to have node-positive disease. Among women with Stage I-IIIC breast cancer, the crude 10-year breast cancer-specific survival rate was 91.0% for Filipino and 88.9% for White women (HR 0.81, 95% CI 0.74-0.88, p < 0.01). In a propensity-matched analysis, the HR was 0.73 (95% CI 0.66-0.81). The survival advantage for Filipino women was present in subgroups defined by age of diagnosis, nodal status, estrogen receptor status, and HER2 receptor status.

CONCLUSION

In the United States, Filipino women often present with more advanced breast cancers than White women, but experience better breast cancer-specific survival.

Salpingectomy and the Risk of Ovarian Cancer in Ontario

Importance

A body of pathological and clinical evidence supports the position that the fallopian tube is the site of origin for a large proportion of high-grade serous ovarian cancers. Consequently, salpingectomy is now considered for permanent contraception (in lieu of tubal ligation) or ovarian cancer prevention (performed opportunistically at the time of surgical procedures for benign gynecologic conditions).

Objective

To evaluate the association between salpingectomy and the risk of invasive epithelial ovarian, fallopian tube, and peritoneal cancer.

Design, Setting, and Participants

This population-based retrospective cohort study included all women aged 18 to 80 years who were eligible for health care services in Ontario, Canada. Participants were identified using administrative health databases from Ontario between January 1, 1992, and December 31, 2019. A total of 131 516 women were included in the primary (matched) analysis. Women were followed up until December 31, 2021.

Exposures

Salpingectomy (with and without hysterectomy) vs no pelvic procedure (control condition) among women in the general population.

Main Outcomes and Measures

Women with a unilateral or bilateral salpingectomy in Ontario between April 1, 1992, and December 31, 2019, were matched 1:3 to women with no pelvic procedure from the general population. Cox proportional hazards regression models were used to estimate the hazard ratios (HRs) and 95% CIs for ovarian, fallopian tube, and peritoneal cancer combined.

Results

Among 131 516 women (mean [SD] age, 42.2 [7.6] years), 32 879 underwent a unilateral or bilateral salpingectomy, and 98 637 did not undergo a pelvic procedure. After a mean (range) follow-up of 7.4 (0-29.2) years in the salpingectomy group and 7.5 (0-29.2) years in the nonsurgical control group, there were 31 incident cancers (0.09%) and 117 incident cancers (0.12%), respectively (HR, 0.82; 95% CI, 0.55-1.21). The HR for cancer incidence was 0.87 (95% CI, 0.53-1.44) when comparing those with salpingectomy vs those with hysterectomy alone.

Conclusions and Relevance

In this cohort study, no association was found between salpingectomy and the risk of ovarian cancer; however, this observation was based on few incident cases and a relatively short follow-up time. Studies with additional years of follow-up are necessary to define the true level of potential risk reduction with salpingectomy, although longer follow-up will also be a challenge unless collaborative efforts that pool data are undertaken.

The association between immigration status and the development of type 2 diabetes in women with a prior diagnosis of gestational diabetes: a population-based study

AIMS

To examine the influence of immigration status and region of origin on the risk of type 2 diabetes in women with prior gestational diabetes (GDM).

METHODS

This retrospective population-based cohort study included women with gestational diabetes (GDM) aged 16 to 50 years in Ontario, Canada who gave birth between 2006-2014. We compared the incidence of type 2 diabetes after delivery between long-term residents and immigrants - overall, by time since immigration, and by region of origin - using Cox regression adjusted for age, year, neighbourhood income, rurality, infant birth weight, and presence of hypertensive disorders of pregnancy (HDP).

RESULTS

Among 38,515 women with prior GDM (42% immigrants), immigrants had a significantly higher risk of type 2 diabetes compared to long-term residents [adjusted hazard ratio (HR) 1.19, 95% confidence interval (CI) 1.13- 1.26], with no meaningful difference based on time since immigration. The highest adjusted relative risks of type 2 diabetes compared to long-term residents were found for immigrants from Sub-Saharan Africa (HR 1.63, 95% CI 1.40-1.90), Latin America/Caribbean (HR 1.44, 95% CI 1.28-1.62) and South Asia (HR 1.34, 95% CI 1.25-1.44).

CONCLUSIONS

Immigration is associated with a significantly higher risk of type 2 diabetes after GDM, particularly for women from certain low- and middle-income countries. Diabetes prevention strategies will need to consider the unique needs of immigrants from these regions.

Abstract P4-03-11: Population-based survival outcomes of pure vs mixed invasive lobular breast carcinoma in Ontario, Canada

Purpose: We aim to determine incidence and survival rates of pure vs mixed invasive lobular breast carcinoma between 1990 and 2020 in the province of Ontario, Canada. We further evaluated patient and tumour factors that predict survival for invasive lobular carcinoma (ILC). Methods: Using population-based administrative healthcare datasets at Institute of Clinical Evaluative Sciences (ICES) Ontario, we calculated the crude 5-year incidence rates of pure ILC versus invasive ductal carcinoma (IDC) versus mixed ILC-IDC in the province of Ontario, Canada between 1990 and 2020. Kaplan-Meier survival curves were generated to determine the 5-, 10-, 15- and 20-year survival for ILC (and mixed ILC-IDC) as compared with IDC. Survival curves were compared using the log-rank test and stratified by stage. Using a multivariable Cox proportional hazards regression analysis, we identified patient (e.g. demographic, geographic, socioeconomic) and tumour (grade, stage, receptor subtype) factors that predicted survival for patients with ILC. Statistical analysis was performed using SAS® and P values &lt; 0.05 were considered statistically significant. Results: We identified 18,551 (8%) pure ILC, 10,234 (4%) mixed ILC-IDC and 192,371 (81%) IDC cases. The crude incidence of pure ILC increased from 55.7 per 100,000 in 1990 to 80.2 per 100,000 in 2020. The crude incidence of mixed ILC-IDC peaked in the mid-2000s at 48.6 per 100,000 and subsequently declined to 32.1 per 100,000 in 2020. There was a significant difference in overall survival between the three breast cancer subtypes. Over a 30-year follow-up period (mean 9.3 +/- 7.3 years), overall survival of mixed ILC-IDC mirrors the survival of pure IDC, while women with pure ILC have inferior survival compared with IDC beginning after 10 years of follow-up (P &lt; .001). The 20-year overall survival was 40% for ILC and 50% for IDC and mixed ILC-IDC. Older age &gt; 55 years (vs. 50-54 years, P &lt; .0001), lowest neighborhood income quintile (HR 1.1, P = .038), geographic location within Ontario (P &lt; .01) and increasing Elixhauser Comorbidity Index score (P &lt; .0001) predicted worse overall survival for ILC patients. Conversely, the increasing number of mammograms received in the five years prior to diagnosis predicted better overall survival (P &lt; .0001). When stratified by cancer stage, the worse survival in ILC (compared with IDC and mixed ILC-IDC) was only observed for stage III patients (P = .01). Stage III and IV disease, grade 3 histology and ER/PR negativity predicted worse survival (P &lt; .01). Conclusion: The crude incidence of ILC is increasing over time. Over a 30-year follow-up period (mean 9.3 +/- 7.3 years), ILC had worse overall survival compared with IDC and mixed ILC-IDC, particular stage III patients. Patient demographic and tumour factors predict overall survival in ILC. While treatment paradigms for ILC mirror that for IDC, our data demonstrates worse overall survival for ILC and a need for more research and treatments focused on improving long-term survival for ILC patients.

Citation Format: David Lim, Vasily Giannakeas, Steven Narod, Kelly Metcalfe. Population-based survival outcomes of pure vs mixed invasive lobular breast carcinoma in Ontario, Canada [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-03-11.

The association between offspring birthweight and future risk of maternal diabetes: A population-based study

AIMS

As an indicator of maternal cardiometabolic health, newborn birthweight may be an important predictor of maternal type 2 diabetes mellitus (diabetes). We evaluated the relation between offspring birthweight and onset of maternal diabetes after pregnancy.

METHODS

This retrospective cohort study used linked population-based health databases from Ontario, Canada. We included women aged 16-50 years without pre-pregnancy diabetes, and who had a live birth between 2006 and 2014. We used Cox proportional hazard regression to evaluate the association between age- and sex-standardized offspring birthweight percentile categories and incident maternal diabetes, while adjusting for maternal age, parity, year, ethnicity, gestational diabetes (GDM) and hypertensive disorders of pregnancy (HDP). Results were further stratified by the presence of GDM in the index pregnancy.

RESULTS

Of 893,777 eligible participants, 14,329 (1.6%) women were diagnosed with diabetes over a median (IQR) of 4.4 (1.5-7.4) years of follow-up. There was a continuous positive relation between newborn birthweight above the 75th percentile and maternal diabetes. Relative to a birthweight between the 50th and 74.9th percentiles, women whose newborn had a birthweight between the 97th and 100th percentiles had an adjusted hazards ratio (aHR) of diabetes of 2.30 (95% CI 2.16-2.46), including an aHR of 2.01 (95% CI 1.83-2.21) among those with GDM, and 2.59 (2.36-2.84) in those without GDM.

CONCLUSIONS

A higher offspring birthweight signals an increased risk of maternal diabetes, offering another potentially useful way to identify women especially predisposed to diabetes.

Contemporary Trends in Breast Reconstruction Use and Impact on Survival Among Women with Inflammatory Breast Cancer

BACKGROUND

Breast reconstruction is generally discouraged in women with inflammatory breast cancer (IBC). Nevertheless, reconstruction rates are increasing in this population.

OBJECTIVE

We aimed to determine contemporary trends and predictors of breast reconstruction use and its impact on mortality among IBC patients.

METHODS

Demographic, clinicopathologic, and follow-up data for women with non-metastatic IBC having mastectomy between 2004 and 2015 were collected from the Surveillance, Epidemiology, and End Results (SEER) 18 registries database. Rates and predictors of immediate breast reconstruction, along with survival outcomes between the breast reconstruction and no reconstruction groups were calculated. To account for selection bias, a propensity score analysis matching one reconstruction patient to three no reconstruction patients was performed.

RESULTS

A total of 4076 women with non-metastatic IBC who underwent mastectomy (388 [9.5%] with breast reconstruction and 3688 [90.5%] without) were included. The proportion of women undergoing breast reconstruction and contralateral prophylactic mastectomy increased from 6.2 to 15.3% and 12.9 to 29.6%, respectively, between 2004 and 2015. Younger age, higher annual income, metropolitan residence, and bilateral mastectomy predicted breast reconstruction use. The 10-year breast cancer-specific survival was 62.9% for women having breast reconstruction and 47.6% for women not having breast reconstruction. After propensity-matched analysis, 10-year cancer-specific survival was similar between the reconstruction (56.6%) and no reconstruction (62.2%) groups (adjusted hazard ratio 0.96, 95% confidence interval 0.79-1.16; p = 0.65).

CONCLUSIONS

Breast reconstruction rates continue to rise among IBC patients, particularly young women and women with access to reconstruction. Breast reconstruction is not associated with inferior breast cancer-specific survival and can be an option for select patients.

High Expression of RECQL Protein in ER-Positive Breast Tumours Is Associated With a Better Survival

Background

RECQL (also known as RECQ1 and RECQL1) is a gene of recent interest in breast cancer and an association between high levels of RECQL protein in breast cancer tumour cells and good survival of patients has been reported.

Methods

To validate this association, we measured the RECQL protein levels in tumours of 933 breast cancer patients using immunohistochemistry analysis and followed the patients for death from breast cancer.

Results

Women with a level of RECQL protein above the 75th percentile had better 15-year disease-specific survival among ER-positive patients (62.5% vs. 48.7%, HR= 0.72, 95%CI= 0.52-0.98, p-value = 0.04), but not among ER- patients (48.9% vs. 48.0%, HR= 1.07, 95%CI= 0.67-1.69, p-value= 0.79). Among the ER-negative patients, high RECQL protein levels were associated with better survival among women who received tamoxifen treatment (67.0% vs. 51.5%, HR= 0.64, 95%CI= 0.41-0.99, p-value= 0.04).

Conclusion

RECQL might be a new predictive marker for tamoxifen treatment among ER-positive patients.

Trends in platelet count among cancer patients

An elevated platelet count has been associated with an increased incidence of cancer and poor survival for many cancer types. In this study, platelet levels were captured among cancer patients in the 2 years prior to and following a cancer diagnosis. I investigated if the trends in platelet count differ between patients that died or did not die from their cancer. For many cancer types, including colon, lung, ovary, and stomach, platelet counts rose as they approached the date of diagnosis. Patients that died from their cancer within 3 years of diagnosis had a higher peak platelet count than those who survived. Following diagnosis, platelet count was elevated among patients that died from their cancer as compared to patients who survived. An elevated platelet count could potentially indicate the presence of an occult cancer or be used as a prognostic measure for cancer-specific survival.

Abstract P3-12-11: Survival differences in Filipino versus white women with breast cancer in the United States: A SEER-based analysis

Purpose: We compared survival rates for American Filipino and White women with breast cancer in the Surveillance, Epidemiology, and End Results (SEER) database diagnosed between 2004 and 2015. Methods: We performed a retrospective cohort study of Filipino and White women with breast cancer diagnosed between 2004 to 2015 in the SEER18 registries database. We collected data on age and year at diagnosis, median household income, marital status, tumour size, tumour grade, lymph node status, stage, receptor status (ER, PR, and HER-2/neu receptor), surgical treatment (lumpectomy versus mastectomy), receipt of chemotherapy and radiotherapy, and death. Filippino and White women were compared for demographic, pathologic and treatment variables and differences were assessed using standardized differences. We compared crude breast cancer-specific mortality rates between the two ethnic groups. We also calculated adjusted hazard ratios (HR) in a propensity-matched design using the Cox proportional hazards model. Women were matched on the year and age at diagnosis (both within 2 years), tumour grade, nodal status, clinical stage, ER status, HER2/neu status and propensity score. The propensity score accounted for marital status, household income, tumour size, PR status and surgical procedure. A log-rank test was used to compare differences between groups using the Kaplan-Meier method. P values &lt; .05 were considered statistically significant. Results: There were 10,834 Filipino women (2.5%) and 414,618 White women (97.5%) with stage I-IV breast cancer captured in the SEER database. Mean age at diagnosis was younger for Filipino women compared with White women (57.5 vs 60.8 years, P &lt; .0001). There was a higher proportion of Filipino women presenting with a higher clinical stage at presentation (P &lt; .0001), node-positivity (35.4% vs 33.4%, P = .0002), and HER-2 positivity (12.1% vs 7.4%, P &lt; .0001) compared with White women. Among women with stage I-IIIC breast cancer, 10-year breast cancer-specific survival was 87.7% for Filipino women, compared with 85.6% for White women. Filipino women had a lower rate of breast cancer-specific death as compared with White women (HR 0.84; 95% CI 0.78 - 0.89; P &lt; .0001). We performed a 1:3 propensity-matched analysis and matched 8,120 Filipino patients to 24,360 white patients. The cancer-specific survival from breast cancer after 10 years of follow-up among matched patients was 92.9% for Filipino women and 90.2% for White women. The hazard ratio in the matched analysis was 0.73 (95% CI 0.66 - 0.81), compared with the crude hazard ratio of 0.84 (95% CI 0.78 - 0.89). The matched analysis demonstrate that Filipino women had better survival than White women overall, and within subgroups defined by age of diagnosis, tumour grade, clinical stage, nodal status, estrogen receptor and HER2 receptor status. The most pronounced effects were observed for HER2 positivity (HR 0.38, 95% CI 0.20-0.71), node-negative patients (HR 0.68, 95% CI 0.57-0.82) and stage II patients (HR 0.68, 95% CI 0.58 - 0.79). Conclusion: Filipino women with breast cancer present with more advanced disease compared to White women but have a better breast cancer-specific survival. Over a 13-year follow-up period, Filipino women with stage I-IIIC breast cancer experienced a 27% reduction in rate of breast cancer death as compared with White women with similar cancers. Compliance with treatment and follow-up or intrinsic biological differences may underlie the improved survival of Filipino women compared with White women, despite presenting with more advanced disease.

Citation Format: David Wai Lim, Vasily Giannakeas, Steven A Narod. Survival differences in Filipino versus white women with breast cancer in the United States: A SEER-based analysis [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-11.

Platelet Count and Survival after Cancer

Simple Summary

Platelets are cellular fragments circulating in the blood that are responsible for clotting. Previous research has shown that cancer patients with an abnormally high platelet count (thrombocytosis) have elevated rates of death from cancer. We aimed to investigate to what extent platelet counts are associated with survival after cancer. We followed a large provincial cohort of cancer patients with a platelet count recorded at the time of their diagnosis. We categorized patients according to platelet count (low, medium, high). Cancer patients in the ‘high’ platelet count category had the highest rate of cancer death, and cancer patients in the ‘low’ platelet count category had the lowest rate of cancer death. Platelet count may be used to predict survival in cancer patients.

Abstract

Thrombocytosis is associated with cancer progression and death for many cancer types. It is unclear if platelet count is also associated with cancer survival. We conducted a cohort study of 112,231 adults in Ontario with a diagnosis of cancer between January 2007 and December 2016. We included patients who had a complete blood count (CBC) completed in the 30 days prior to their cancer diagnosis. Subjects were assigned to one of three categories according to platelet count: low (≤25th percentile), medium (>25 to <75th percentile), and high (≥75th percentile). Study subjects were followed from the date of their cancer diagnosis for cancer-specific death. Of the 112,231 eligible cancer patients in the cohort study, 40,329 (35.9%) died from their cancer in the follow-up period. Relative to those with a medium platelet count, the rate of cancer-specific death was higher among individuals with a high platelet count (HR 1.52; 95%CI 1.48–1.55) and was lower among individuals with a low platelet count (HR 0.91; 95%CI 0.88–0.93). A high platelet count was associated with poor survival for many cancer types. Platelet count could potentially be used as a risk stratification measure for cancer patients.

Analysis of Platelet Count and New Cancer Diagnosis Over a 10-Year Period

IMPORTANCE

Individuals with cancer often have an elevated platelet count at the time of diagnosis. The extent to which an elevated platelet count is an indicator of cancer is unclear.

OBJECTIVE

To evaluate the association of an elevated platelet count with a cancer diagnosis.

DESIGN, SETTING, AND PARTICIPANTS

This nested case-control study included Ontario residents enrolled in the provincial health insurance plan who had 1 or more routine complete blood count (CBC) tests performed between January 1, 2007, and December 31, 2017, with follow-up through December 31, 2018. Case patients were individuals with a new cancer diagnosis during the observation period. Eligible control individuals were cancer free before the date of diagnosis for a case patient to whom they were matched. One case patient was matched to 3 controls based on sex, age, and health care use patterns. Data were analyzed from September 24, 2020, to July 13, 2021.

EXPOSURES

Case patients and controls were assigned to 1 of 5 exposure groups based on age- and sex-specific platelet count distributions in the control population: very low (≤10th percentile), low (>10th to 25th percentile), medium (>25th to <75th percentile), high (75th to <90th percentile), and very high (≥90th percentile).

MAIN OUTCOMES AND MEASURES

Odds ratios (ORs) were estimated for specific cancer sites for each category of platelet count at intervals up to 10 years after a blood test.

RESULTS

Of the 8 917 187 eligible Ontario residents with a routine CBC record available, 4 971 578 (55.8%) were women; the median age at the first CBC was 46.4 years (IQR, 32.5-59.5 years). Among individuals with a routine CBC record available, 495 341 (5.6%) received a diagnosis of first primary cancer during the 10-year observation period. The OR for a solid tumor diagnosis associated with a very high platelet count vs a medium platelet count in the 6-month period before the diagnosis was 2.32 (95% CI, 2.28-2.35). A very high platelet count was associated with colon (OR, 4.38; 95% CI, 4.22-4.54), lung (OR, 4.37; 95% CI, 4.22-4.53), ovarian (OR, 4.62; 95% CI, 4.19-5.09), and stomach (OR, 4.27; 95% CI, 3.91-4.66) cancers. Odds ratios attenuated with increasing time from CBC test to cancer diagnosis.

CONCLUSIONS AND RELEVANCE

In this nested case-control study, an elevated platelet count was associated with increased risk of cancer at several sites. Our findings suggest that an elevated platelet count could potentially serve as a marker for the presence of some cancer types.

Periodic screening for breast and cervical cancer in women with diabetes: a population-based cohort study

PURPOSE

Diabetes is associated with poorer cancer outcomes. Screening for breast and cervical cancer is recommended by clinical guidelines; however, utilization of these tests in people with diabetes has been unclear due to methodological limitations in the evidence base. We used administrative data to determine the association between diabetes and the rates of becoming up-to-date with periodic breast and cervical cancer screening over a 20-year period.

METHODS

Healthcare databases from Ontario, Canada, were linked to assemble two population-based cohorts of 50-70 and 21-70 year-olds between 1994 and 2011, eligible for breast and cervical cancer screening, respectively. Using age as the time scale, multivariable recurrent events models were implemented to examine the association between the presence of diabetes and the rates of becoming up-to-date with the recommended cancer screenings.

RESULTS

In each of the breast and cervical cancer screening cohorts, there were, respectively, 1,516,302 (16% had diabetes at baseline) and 4,751,220 (9.5% had diabetes at baseline) screen-eligible women. In multivariable models, prevalent diabetes (duration ≥ 2 years) was associated with lower rates of becoming up-to-date with cervical (hazard ratio, HR 0.85, 95% confidence interval, CI 0.84-0.85) and breast (HR 0.94, CI 0.93-0.94) cancer screening, compared to no diabetes.

CONCLUSIONS

Having diabetes is associated with decreased rates of becoming up-to-date with two recommended periodic cancer screenings, with a bigger reduction in the rates of becoming up-to-date with cervical cancer screening. Greater attention to cervical cancer preventive services is needed in women with diabetes.

Incidence of Cancer Among Adults With Thrombocytosis in Ontario, Canada

IMPORTANCE

Individuals with newly diagnosed cancer often have a high platelet count (thrombocytosis). Whether thrombocytosis is associated with the presence of an undiagnosed cancer remains unknown.

OBJECTIVE

To assess whether a new diagnosis of thrombocytosis is associated with a subsequent risk of cancer among adults.

DESIGN, SETTING, AND PARTICIPANTS

This population-based retrospective cohort study was conducted using linked laboratory data from Ontario, Canada, from January 1, 2007, to December 31, 2017, with follow-up until December 31, 2018. The study cohort included adults aged 40 to 75 years on the date of a routine complete blood count (CBC) test (index test) who had a normal platelet count in the 2 previous years and no history of cancer. Data analysis was performed in December 2020.

EXPOSURES

Exposed individuals were those with a platelet count greater than 450 × 109/L. Matched unexposed control individuals had a platelet count within the reference range (150 × 109/L to 450 × 109/L) reported within 30 days of the exposure.

MAIN OUTCOMES AND MEASURES

Incident cancers within 5 years after diagnosis of thrombocytosis. Absolute and relative risks for cancer associated with thrombocytosis were estimated for all cancers and for cancers at specific sites.

RESULTS

Of the 3 386 716 Ontario residents with a recorded routine CBC test result, 53 339 (1.6%) had thrombocytosis and a prior normal platelet count. Among individuals with thrombocytosis, the median age was 59.7 years (interquartile range, 50.2-67.4 years) and 37 349 (70.0%) were women. Among the 51 624 individuals with thrombocytosis included in the matched analysis, 2844 (5.5%) had received a diagnosis of a solid cancer in the 2-year follow-up period and 3869 (7.5%) had received a diagnosis within 5 years. The relative risk (RR) for developing any solid cancer within 2 years was 2.67 (95% CI, 2.56-2.79). Associations were found between thrombocytosis and cancers of the ovary (RR, 7.11; 95% CI, 5.59-9.03), stomach (RR, 5.53; 95% CI, 4.12-7.41), colon (RR, 5.41; 95% CI, 4.80-6.10), lung (RR, 4.41; 95% CI, 4.02-4.85), kidney (RR, 3.64; 95% CI, 2.94-4.51), and esophagus (RR, 3.64; 95% CI, 2.46-5.40).

CONCLUSIONS AND RELEVANCE

In this cohort study, an increased platelet count was associated with an increased risk of cancer for at least 2 years. The results suggest that individuals with unexplained thrombocytosis should be offered screening for several cancers.

The risk of contralateral breast cancer: a SEER-based analysis

BACKGROUND

We sought to estimate the annual risk and 25-year cumulative risk of contralateral breast cancer among women with stage 0-III unilateral breast cancer.

METHODS

We identified 812,851 women with unilateral breast cancer diagnosed between 1990 and 2015 in the SEER database and followed them for contralateral breast cancer for up to 25 years. Women with a known bilateral mastectomy were excluded. We calculated the annual risk of contralateral breast cancer by age at diagnosis, by time since diagnosis and by current age. We compared risks by ductal carcinoma in situ (DCIS) versus invasive disease, by race and by oestrogen receptor (ER) status of the first cancer.

RESULTS

There were 25,958 cases of contralateral invasive breast cancer diagnosed (3.2% of all patients). The annual risk of contralateral breast cancer over the 25-year follow-up period was 0.37% and the 25-year actuarial risk of contralateral invasive breast cancer was 9.9%. The annual risk varied to a small degree by age of diagnosis, by time elapsed since diagnosis and by current age. The 25-year actuarial risk was similar for DCIS and invasive breast cancer patients (10.1 versus 9.9%). The 25-year actuarial risk was higher for black women (12.7%) than for white women (9.7%) and was lower for women with ER-positive breast cancer (9.5%) than for women with ER-negative breast cancer (11.2%).

CONCLUSIONS

Women with unilateral breast cancer experience an annual risk of contralateral breast cancer ~0.4% per year, which persists over the 25-year follow-up period.

Survival Differences in Chinese Versus White Women With Breast Cancer in the United States: A SEER-Based Analysis

PURPOSE

The affect of race on breast cancer prognosis is not well understood. We compared crude and adjusted breast cancer survival rates of Chinese women versus White women in the United States.

METHODS

We conducted a cohort study of Chinese and White women with breast cancer diagnosed between 2004 to 2015 in the SEER 18 registries database. We abstracted information on age at diagnosis, tumor size, grade, lymph node status, receptor status, surgical treatment, receipt of radiotherapy and chemotherapy, and death. We compared crude breast cancer–specific mortality between the two ethnic groups. We calculated adjusted hazard ratios (HRs) in a propensity-matched design using the Cox proportional hazards model. P < .05 was considered statistically significant.

RESULTS

There were 7,553 Chinese women (1.8%) and 414,618 White women (98.2%) with stage I-IV breast cancer in the SEER database. There were small differences in demographics, nodal burden, and clinical stage between Chinese and White women. Ten-year breast cancer–specific survival was 88.8% for Chinese women and 85.6% for White women (HR, 0.73; 95% CI, 0.67 to 0.80; P < .0001). In a propensity-matched analysis among women with stage I–IIIC breast cancer, the HR was 0.71 (95% CI, 0.62 to 0.81; P < .0001). Annual mortality rates in White women exceeded those in Chinese women for the first 9 years after diagnosis.

CONCLUSION

Chinese women in the United States have superior breast cancer–specific survival compared with White women. The reason for the observed difference is not clear. Differences in demographic and tumor features between Chinese and White women with breast cancer may contribute to the disparity, as may the possibility of intrinsic biologic differences.

Evidence of a gabapentinoid and diuretic prescribing cascade among older adults with lower back pain

BACKGROUND/OBJECTIVES

Gabapentinoids are commonly prescribed to relieve pain. The development of edema, an established adverse effect of gabapentinoids, may lead to a potentially harmful prescribing cascade whereby individuals are subsequently prescribed diuretics and exposed to diuretic-induced adverse events. The frequency of this prescribing cascade is unknown. Our objective was to measure the association between new dispensing of a gabapentinoid and the subsequent dispensing of a diuretic in older adults with new low back pain.

DESIGN

Population-based cohort study.

SETTING

Ontario, Canada.

PARTICIPANTS

A total of 260,344 community-dwelling adults aged 66 years or older, newly diagnosed with low back pain between April 1, 2011, and March 31, 2019.

MEASUREMENTS

Exposure status was assigned using dispensed medications in the 1 week after low back pain diagnosis. Older adults newly dispensed a gabapentinoid (N = 7867) were compared with older adults who were not newly dispensed a gabapentinoid (N = 252,477). Hazard ratios (HRs) with 95% confidence intervals (CIs) for dispensing of a diuretic within 90 days of follow-up among older adults prescribed gabapentin relative to those who were not.

RESULTS

Older adults newly dispensed a gabapentinoid had a higher risk of being subsequently dispensed a diuretic within 90 days compared with older adults who were not prescribed a gabapentinoid (2.0% vs. 1.3%). After covariate adjustment, new gabapentinoid users had a higher rate of being dispensed a diuretic compared with those not prescribed a gabapentinoid (HR: 1.44, 95% CI: 1.23, 1.70). The rate of diuretic prescription among new gabapentinoid users increased with increasing gabapentinoid dosages.

CONCLUSIONS

We have demonstrated the presence of a potentially inappropriate and harmful prescribing cascade. Given the widespread use of gabapentinoids, the population-based scale of this problem may be substantial. Increased awareness of this prescribing cascade is required to reduce the unnecessary use of diuretics and the exposure of patients to additional adverse drug events.

Abstract PS7-39: Survival differences in chinese versus white women with breast cancer in the United States: A SEER-based analysis

Purpose: Several studies have reported lower breast cancer survival rates among Black women compared to White women, but less is known regarding outcomes in Chinese women. We compared survival rates for Chinese and White women with breast cancer in the Surveillance, Epidemiology, and End Results (SEER) database diagnosed between 2004 and 2015.

Methods: We conducted a cohort study of Chinese and White women with breast cancer diagnosed between 2004 to 2015 in the SEER18 registries database. We abstracted information on age and year of diagnosis, marital status, median household income, tumour size and grade, lymph node status, clinical stage, receptor status (estrogen, progesterone, and HER-2/neu receptor), surgical treatment (lumpectomy versus mastectomy), receipt of radiotherapy and chemotherapy, and death. Chinese and White women were compared for demographic, pathologic and treatment variables and differences were assessed using standardized differences. Our primary outcome was death from breast cancer. We compared crude breast cancer-specific mortality rates between the two ethnic groups. We also calculated adjusted hazard ratios (HR) in a propensity-matched design using the Cox proportional hazards model. Women were matched on the year of diagnosis and age at diagnosis (both within 2 years), tumour grade, nodal status, clinical stage, estrogen receptor status, HER2/neu status and propensity score. The propensity score accounted for marital status, household income, tumour size, progesterone receptor status and surgical procedure. A log-rank test was used to compare differences between groups using the Kaplan-Meier method. P values &lt; .05 were considered statistically significant.

Results: There were 7,553 Chinese women (1.8%) and 414,618 White women (98.2%) with stage I-IV breast cancer registered in the SEER database. There were only small differences in tumour size, stage at presentation, node-positivity, the proportion of HER2-positive cancers, and the treatments received. Among women with stage I-IIIC breast cancer, 10-year breast cancer-specific survival was 88.8% for Chinese women, compared with 85.6% for White women. The cumulative mortality from breast cancer after 11 years of follow-up was 12.9% for Chinese women and 16.4% for White women; crude HR 0.73 (95% CI 0.67 - 0.80; P &lt; .0001). In the first nine years after diagnosis, annual mortality rates are higher in White women than for Chinese women. Following the first nine years after diagnosis, the annual mortality rate for Chinese women then exceeds that of White women. In a propensity-matched analysis, the cumulative mortality from breast cancer after 11 years of follow-up was 8.9% for Chinese women and 11.9% for White women (P = .0002). The adjusted hazard ratio was 0.71 (95% CI 0.62 - 0.81) and was similar to the crude hazard ratio of 0.73 (95% CI 0.67 - 0.90). The adjusted hazard ratios demonstrate that Chinese women had better survival than White women in subgroups defined by age of diagnosis, tumour size and grade, clinical stage, nodal status and estrogen receptor status. The largest effects were observed for stage I cancers (HR 0.57, 95% CI 0.36-0.90) and for node-negative cancers (HR 0.61, 95% CI 0.46-0.82).

Conclusion: Chinese women diagnosed with breast cancer in the SEER database between 2004 to 2015 had significantly better survival rates than White women with breast cancer. Over a 10-year follow-up period, Chinese women with stage I-IIIC breast cancer experienced a 30% lower risk of death than a comparable group of White women with breast cancer. The observed difference cannot be accounted for by clinical presentation or by differences in treatment and suggests that there are intrinsic biological differences in breast cancer between Chinese and White women.

Citation Format: David Wai Lim, Vasily Giannakeas, Steven A Narod. Survival differences in chinese versus white women with breast cancer in the United States: A SEER-based analysis [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-39.

Bisphosphonate Use Is Protective of Radiographic Knee Osteoarthritis Progression Among those With Low Disease Severity and Being Non-Overweight: Data From the Osteoarthritis Initiative

Antiresorptive medications have been explored for treating knee osteoarthritis (OA); however, little data exist on the effects of today's more potent nitrogen-containing oral bisphosphonates on radiographic disease-progression in patients with varying disease-severity, especially those who are not overweight. The primary objective of this cohort study was to determine if the use of bisphosphonates is protective against 2-year radiographic-progression of knee OA in Osteoarthritis Initiative (OAI) participants, stratified by baseline radiographic disease status. Secondary objectives were to examine effects in non-overweight participants (body mass index [BMI] < 25 kg/m² ) and cumulative bisphosphonate exposure effects. We identified female OAI participants aged ≥50 years and excluded those missing baseline radiograph readings, bisphosphonate use information, or all clinical questionnaire information at baseline. Participants reporting bisphosphonate use (69% alendronate) were propensity-matched 1:1 to non-bisphosphonate users and followed until first radiographic knee OA progression (1-unit increase in Kellgren and Lawrence [KL] grade) or data were censored (first missed visit or end of 2-year follow-up). Discrete-time logistic regression models estimated hazard ratios (HRs) between bisphosphonate users versus nonusers, with an interaction term for baseline KL grade (KL <2 or KL ≥2). We identified 1977 eligible women (n = 346 bisphosphonate users). Propensity-matched results indicated that bisphosphonate users with KL grade <2 were protected against progression (HR_KL<2 0.53; 95% CI, 0.35 to 0.79), while bisphosphonate use was not associated with radiographic progression in those with KL grade ≥2 (HR_KL≥2 1.06; 95% CI, 0.83 to 1.35). When restricting analyses to those with BMI <25 kg/m² , effects were strengthened (HR_KL<2 0.49 [95% CI, 0.26 to 0.92]; HR_KL≥2 0.69 [95% CI, 0.33 to 1.26]). Duration of bisphosphonate use had no effect on progression, though sample size was limited. Bisphosphonate therapy may be protective against radiographic knee OA progression in early-stage patients, particularly those who are non-overweight, but less so for those with more advanced disease or more weight-bearing joint stress. © 2020 American Society for Bone and Mineral Research (ASBMR).

A Validation of Methods for the Evaluation of Observational Studies of Screening Mammography: An Exploratory Analysis Based on Simulating Screening Cohorts

Background

The degree of confidence one should place on non-randomised observational trials studies which estimate the benefit of screening depends on the validity of the analytic method employed. As is the case for all observational trials, screening evaluation studies are subject to bias. The objective of this study was to create a simulated data set and to compare four analytic methods in order to identify the method which was the least biased in terms of estimating the underlying hazard ratio.

Methods

We simulated a cohort of 100,000 women who were accorded US national rates of breast cancer incidence and breast cancer mortality over their lifetime. We assigned at random one-half of them to initiate mammography screening between ages 50 and 60. We used four different analytic approaches to estimate the hazard ratio under a null model (true HR = 1.0) and under a protective model (true HR = 0.80). Two models used the entire data set (with and without including mammography as a time-dependent covariate) and two models invoked matching of screened women with unscreened women (with and without excluding of women who had a mammogram after study initiation). For each of the four analytic methods, we compared the observed hazard ratio with the true hazard ratio. We considered an analytic method to be valid if the observed hazard ratio was close to the true hazard ratio.

Results

Two simple analytic methods generated biased results that led to spurious protective effects observed when none was there. The least biased method was based on matching screened and unscreened women and which emulated a randomized trial design, wherein the unexposed control had no mammogram prior to study entry, but she was not excluded or censored if she had a mammogram after the index date.

Conclusion

There is no single ideal method to analyze observational data to evaluate the effectiveness of screening mammography (ie, which generates an unbiased estimates of the underlying hazard ratio) but designs which emulate randomised trials should be promoted.

Association of a Diagnosis of Ductal Carcinoma In Situ With Death From Breast Cancer

IMPORTANCE

It is not clear to what extent a diagnosis of ductal carcinoma in situ (DCIS) impacts a woman's lifetime risk of dying of breast cancer. Under ideal circumstances, treatment will eliminate the risk of invasive ipsilateral recurrence and prevent subsequent mortality from breast cancer. The risk of dying of breast cancer after a diagnosis of DCIS had not been compared with that of women without cancer in the general population.

OBJECTIVE

To determine the risk of death from breast cancer in a large cohort of patients treated for DCIS and to compare the risk with that of women in the general population.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included data for women who had first primary DCIS diagnosed between 1995 and 2014 from the Surveillance, Epidemiology and End Results (SEER) registries database. Women with DCIS underwent surgical treatment, and approximately half also received radiotherapy. These women were followed from the date of DCIS diagnosis until death from breast cancer or date of last follow-up. Women in the general population without breast cancer were analyzed as controls. Follow-up information was available up to December 2016. The data were analyzed in March 2020.

EXPOSURES

Patients with DCIS who underwent surgical treatment.

MAIN OUTCOMES AND MEASURES

Breast cancer death was the main outcome. Standardized mortality ratios were estimated by comparing deaths from breast cancer among women diagnosed with DCIS with expected deaths from breast cancer among women in the general population who did not have cancer. Expected probability of death from breast cancer in the general population was calculated by an incidence-based mortality approach using standardized SEER-based incidence and case-fatality rates. Probability of breast cancer death was estimated based on the assumption that a cancer-free control was cancer free on the date the woman with DCIS was diagnosed and was studied until the end of follow-up.

RESULTS

A total of 144 524 women diagnosed with first primary DCIS were included (mean [SD] age at diagnosis, 57.4 [11.0] years). There were 1540 deaths from breast cancer in the cohort. Based on SEER-based incidence and case-fatality rates, 458 breast cancer deaths were expected in an equivalent number of cancer-free women from the general population with equal follow-up. The standardized mortality ratio for death from breast cancer among women with DCIS was 3.36 (95% CI, 3.20-3.53). The elevated risk of death persisted more than 15 years after diagnosis.

CONCLUSIONS AND RELEVANCE

In the population studied, the risk of dying of breast cancer was increased 3-fold after a diagnosis of DCIS. This suggests that our current treatment focus on preventing invasive recurrence is insufficient to eliminate all deaths from breast cancer after DCIS.

Evaluation of a Common Prescribing Cascade of Calcium Channel Blockers and Diuretics in Older Adults With Hypertension

IMPORTANCE

Calcium channel blockers (CCBs) are commonly prescribed agents for hypertension that can cause peripheral edema. A prescribing cascade occurs when the edema is misinterpreted as a new medical condition and a diuretic is subsequently prescribed to treat the edema. The extent to which this prescribing cascade occurs at a population level is not well understood.

OBJECTIVE

To measure the association between being newly dispensed a CCB and subsequent dispensing of a loop diuretic in older adults with hypertension.

DESIGN, SETTING, AND PARTICIPANTS

A population-based cohort study was performed using linked health administrative databases of community-dwelling adults 66 years or older with hypertension and new prescription drug claims from September 30, 2011, to September 30, 2016, in Ontario, Canada. The dates of analysis were September 1, 2018, to May 30, 2019.

EXPOSURES

Individuals who were newly dispensed a CCB were compared with the following 2 groups: (1) individuals who were newly dispensed an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker and (2) individuals who were newly dispensed an unrelated medication.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) with 95% CIs were estimated for individuals who were dispensed a loop diuretic within 90 days of follow-up using Cox proportional hazards regression models.

RESULTS

The cohort included 41 086 older adults (≥66 years) with hypertension who were newly dispensed a CCB, 66 494 individuals who were newly dispensed another antihypertensive medication, and 231 439 individuals who were newly dispensed an unrelated medication. At index (ie, the dispensing date), the mean (SD) age was 74.5 (6.9) years, and 191 685 (56.5%) were women. Individuals who were newly dispensed a CCB had a higher cumulative incidence at 90 days of being dispensed a loop diuretic than individuals in both control groups (1.4% vs 0.7% and 0.5%, P < .001). After adjustment, individuals who were newly dispensed a CCB had increased relative rates of being dispensed a loop diuretic compared with individuals who were newly dispensed an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (HR, 1.68; 95% CI, 1.38-2.05 in the first 30 days after index [days 1-30]; 2.26; 95% CI, 1.76-2.92 in the subsequent 30 days [days 31-60]; and 2.40; 95% CI, 1.84-3.13 in the third month of follow-up [days 61-90]) and individuals who were newly dispensed unrelated medications (HR, 2.51; 95% CI, 2.13-2.96 for 1-30 days after index; 2.99; 95% CI, 2.43-3.69 for 31-60 days after index; and 3.89; 95% CI, 3.11-4.87 for 61-90 days after index). This association persisted, although slightly attenuated, from 90 days to up to 1 year of follow-up and when restricted to a subgroup of individuals who were newly dispensed amlodipine.

CONCLUSIONS AND RELEVANCE

Many older adults with hypertension who are newly dispensed a CCB subsequently receive a loop diuretic. Given how widely CCBs are prescribed, interventions are needed to raise clinicians' awareness of this common prescribing cascade to reduce the prescribing of potentially unnecessary medications that may cause harm.

Impact of diabetes on colorectal cancer stage and mortality risk: a population-based cohort study

AIMS/HYPOTHESIS

Diabetes is associated with an increased incidence of colorectal cancer (CRC). There exists conflicting evidence regarding the impact of diabetes on CRC-specific mortality (herein also referred to as cancer-specific mortality). The objectives of this study were to determine whether diabetes is associated with a more advanced CRC stage at diagnosis and with higher all-cause and cancer-specific mortality.

METHODS

This retrospective cohort study used linked, population-based health databases from Ontario, Canada. Among individuals diagnosed with CRC from 2007 to 2015, we compared the likelihood of presenting with later- (III or IV) vs early- (I or II) stage CRC between patients with and without diabetes adjusting for relevant covariates. We then determined the association between diabetes and all-cause and CRC-specific mortality, after adjusting for CRC stage at diagnosis and other covariates.

RESULTS

Of the 44,178 individuals with CRC, 11,822 (26.7%) had diabetes. After adjustment for CRC screening and other covariates, individuals with diabetes were not more likely to present with later-stage CRC (adjusted OR 0.97, 95% CI 0.93, 1.01). Over a median follow-up of 2.63 (interquartile range [IQR] 0.97-5.10) years, diabetes was associated with higher all-cause mortality (adjusted HR 1.08, 95% CI 1.04, 1.12) but similar cancer-specific survival (adjusted HR 1.0, 95% CI 0.95, 1.06).

CONCLUSIONS/INTERPRETATION

Individuals with diabetes who develop CRC are not more likely to present with a later stage of CRC and have similar cancer-specific mortality compared with those without diabetes. Diabetes was associated with higher all-cause mortality in CRC patients, indicating that greater attention to non-cancer care is needed for CRC survivors with diabetes.

Effectiveness of confidential reports to physicians on their prescribing of antipsychotic medications in nursing homes

Background

Antipsychotic medication use in nursing homes is associated with potential for harms. In Ontario, Canada, an agency of the provincial government offers nursing home physicians quarterly audit and feedback on their antipsychotic prescribing. We compared the characteristics of physicians who did and did not engage with the intervention, and assessed early changes in prescribing.

Methods

This population-level, retrospective cohort study used linked administrative databases to track prescribing practices in nursing homes pre-intervention (baseline), immediately post-initiative (3 months), and at follow-up (6 months). Exposure variables identified whether a physician signed up to participate (or not) or viewed the feedback following sign up (or not). Differences in the proportion of days that residents received antipsychotic medications at 6 months compared to baseline by exposure(s) were assessed using a linear mixed effects regression analysis to adjust for a range of resident, physician, and nursing home factors. Benzodiazepine and statin prescribing were assessed as a balance and tracer measures, respectively.

Results

Of 944 eligible physicians, 210 (22.3%) signed up to recieve the feedback report and 132 (13.9%) viewed their feedback. Physicians who signed up for feedback were more likely to have graduated from a Canadian medical school, work in urban nursing homes, and care for a larger number of residents. The clinical and functional characteristics of residents were similar across physician exposure groups. At 6 months, antipsychotic prescribing had decreased in all exposure groups. Those who viewed their feedback report had a signicantly greater reduction in antipsychotic prescribing than those who did not sign up (0.94% patient-days exposed; 95% CI 0.35 to 1.54%, p = 0.002). Trends in prescribing patterns across exposure groups for benzodiazepines and statins were not statistically significant.

Interpretation

Almost a quarter of eligible physicians engaged early in a voluntary audit and feedback intervention related to antipsychotic prescribing in nursing homes. Those who viewed their feedback achieved a small but statistically significant change in prescribing, equivalent to approximately 14,000 fewer days that nursing home residents received antipsychotic medications over 6 months. This study adds to the literature regarding the role of audit and feedback interventions to improve quality of care.

Abstract P5-07-07: A generalizable relationship between mortality and time-to-death among breast cancer patients can be explained by tumor dormancy

Background: Women with ER-positive breast cancer may recur as late as twenty years post diagnosis. The reason for this delayed recurrence is unknown. We studied survival patterns, including time-to-death in 123,705 women with stage I to III invasive breast cancer, enrolled in the SEER database. We sought to determine if time from diagnosis to death could be explained by variation in tumor dormancy.

Methods: We divided the cohort into ten classes based on their 20-year risks of death from breast cancer. Probability of death at 20 years was estimated for each patient using year of diagnosis, patient characteristics (age, race, household income), tumor characteristics (grade, tumor size, nodal status, stage, ER and PR-status) and treatment (radiotherapy, chemotherapy). The 20-year mortality for women in the highest risk decile (decile 10) was 69% versus 5% for women in the lowest decile (decile 1). We define a variable α which represents the annual rate of reactivation from tumor dormancy. Using the highest risk decile as a reference distribution, we determined what α value gives the best fit for the time-to-death distribution of each decile. As a complementary analysis we performed quantile regression to determine independent predictors of time-to-death among women who died from breast cancer.

Results: The duration of tumor dormancy was much longer, on average, for ER-positive breast cancers than for ER-negative breast cancers. Time at peak mortality rate monotonically decreased by decile, ranging from 19 years post-diagnosis in the lowest risk decile to two years post-diagnosis in the highest risk decile (Table 1). The difference in the time-to-death distributions by decile could be explained by the variable α which represents the annual rate of reactivation from tumor dormancy.

In the regression analysis, ER-positive breast cancers had a median time-to-death 3.67 years longer than ER-negative breast cancers (Table 2). However, this effect was attenuated by risk factors correlated with ER status (adjusted difference 1.76 years). Notable independent predictors of time-to-death include ethnicity, tumor size, grade, nodal status and PR-status.

Conclusion: Reactivation from tumor dormancy appears to occur at random wherein the rate of tumor activation is correlated with probability of death from breast cancer. This model may explain the very long time to cancer recurrence in women with ER-positive node-negative breast cancers. The clinical course of women with low-risk breast cancer is inherently unpredictable.

Table 1: Factors related to breast cancer mortality and time-to-death by decile.Risk DecileNumber of patients (N)Annual death rate (per 100 person-years)20-year actuarial mortality (%)Peak mortality time (years)Median time-to-death (years)10th percentile time-to-death (years)90th percentile time-to-death (years)Optimal α (reactivations per person-year)112,3700.255.3%19.012.24.018.70.10212,3710.438.6%19.511.04.318.40.16312,3700.6011.3%9.510.33.517.60.20412,3710.7413.2%5.58.93.016.70.32512,3700.9016.0%3.58.62.617.40.32612,3711.1720.0%4.08.12.616.90.35712,3711.5124.8%3.07.62.316.70.41812,3702.1231.7%3.06.41.915.90.74912,3713.2242.5%2.55.61.714.81.291012,3706.6463.0%2.03.81.112.3InF (Ref.)

Table 2: Predictors of time-to-death in breast cancer patients.PredictorValueUnadjustedAdjustedMedian time-to-death (years)Difference* (years)Difference (years)**POverall/ Reference5.6713.05***&lt;.0001Year of diagnosis19905.42Reference19915.670.250.170.360919925.670.250.220.289919935.580.170.350.059919946.000.580.530.0054Age at diagnosis&lt;505.58Reference50-595.920.330.070.580760-696.170.58-0.060.655170-805.25-0.33-1.18&lt;.0001EthnicityWhite5.75ReferenceBlack4.33-1.42-0.320.009East Asian6.670.920.930.0058Southeast Asian6.080.330.090.8208Other/Unknown6.170.420.420.4176Tumor size (cm)&lt;1cm8.33Reference1-2cm7.33-1.00-0.650.07922-3cm5.58-2.75-1.42&lt;.00013-5cm4.75-3.58-1.76&lt;.00015+cm3.83-4.50-2.16&lt;.0001Tumor gradeI11.17ReferenceII7.58-3.58-2.82&lt;.0001III4.25-6.92-4.78&lt;.0001IV3.92-7.25-5.18&lt;.0001Unknown6.25-4.92-3.57&lt;.0001Nodal statusN06.83ReferenceN15.67-1.17-0.69&lt;.0001N25.00-1.83-1.08&lt;.0001N33.83-3.00-2.03&lt;.0001Unknown2.42-4.42-2.32&lt;.0001ER statusPositive7.17ReferenceNegative3.50-3.67-1.76&lt;.0001PR statusPositive7.25ReferenceNegative3.83-3.42-1.7&lt;.0001Unknown5.08-2.17-1.35&lt;.0001RadiotherapyNo5.42ReferenceYes6.080.670.260.0214Unknown5.08-0.33-0.470.1043ChemotherapyNo/Unknown6.58ReferenceYes5.17-1.42-0.310.0091*Difference in median time-to-death relative to reference value.**Independent difference in median time-to-death after adjusting for all covariates in table.***Median time-to-death of the reference group.

Citation Format: Vasily Giannakeas, Steven A Narod. A generalizable relationship between mortality and time-to-death among breast cancer patients can be explained by tumor dormancy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-07-07.

Sex Differences in the Prevalent Use of Oral Formulations of Cholinesterase Inhibitors in Older Adults with Dementia

BACKGROUND

Cholinesterase inhibitors (ChEIs) are one of only two drug therapies available to manage cognitive decline in dementia. Given sex-specific differences in medication access and effects, it is important to understand how ChEIs are used by women and men.

OBJECTIVE

The objective of this study was to provide contemporary sex-stratified evidence on patterns of ChEI use by community-dwelling older adults with dementia to inform opportunities to optimize drug prescribing.

METHODS

We conducted a population-based cross-sectional study examining ChEI use in older adults with dementia in Ontario, Canada. We identified all community-dwelling individuals aged 66 years and older with a pre-existing diagnosis of dementia as of 1 April, 2016. We examined the prevalence of ChEI use among women and men separately, and explored the association between ChEI use and age, sex, income status, geographic location of residence, use of palliative care services, comorbidity, and polypharmacy. Concurrent use of drugs known to impair cognition (including antipsychotics, benzodiazepines, and medications with strong anticholinergic properties) was separately assessed among women and men using multivariable analyses and prevalence risk ratios.

RESULTS

Of 74,799 women and 52,231 men living with dementia in the community, nearly 30% currently were using a ChEI (29.3% women, 28.6% men). Close to 70% of users were receiving the target therapeutic dose. Compared to men, women were less often taking the target therapeutic dose (67.8% women vs. 71.6% men, p < 0.001). Over 20% of users also were using drugs known to impair cognition, while being treated for cognitive decline using ChEIs. Compared to men, women were more often concurrently using drugs known to impair cognition (23.9% women vs. 21.8% men, p < 0.001).

CONCLUSIONS

This is one of the first studies of ChEI use to account for important sex differences. The results remind clinicians and researchers that patterns of ChEI therapy use differ by sex, as women were less likely to receive target therapeutic doses and more vulnerable to potentially problematic polypharmacy than men.

Sex-Specific Differences in End-of-Life Burdensome Interventions and Antibiotic Therapy in Nursing Home Residents With Advanced Dementia

IMPORTANCE

Nursing home residents with advanced dementia have limited life expectancies yet are commonly subjected to burdensome interventions at the very end of life. Whether sex-specific differences in the receipt of these interventions exist and what levels of physical restraints and antibiotics are used in this terminal setting are unknown.

OBJECTIVE

To evaluate the population-based frequency, factors, and sex differences in burdensome interventions and antibiotic therapy among nursing home residents with advanced dementia.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study from Ontario, Canada, used linked administrative databases held at ICES, including the Continuing Care Resident Reporting System Long-Term Care database, which contains data from the Resident Assessment Instrument Minimum Data Set, version 2.0. Nursing home residents (n = 27 243) with advanced dementia who died between June 1, 2010, and March 31, 2015, at 66 years or older were included in the analysis. Initial statistical analysis was completed in May 2017, and analytical revisions were conducted from November 2018 to January 2019.

EXPOSURE

Sex of the nursing home resident.

MAIN OUTCOMES AND MEASURES

Burdensome interventions (transitions of care, invasive procedures, and physical restraints) and antibiotic therapy in the last 30 days of life.

RESULTS

The final cohort included 27 243 nursing home residents with advanced dementia (19 363 [71.1%] women) who died between June 1, 2010, and March 31, 2015, at the median (interquartile range) age of 88 (83-92) years. In the last 30 days of life, burdensome interventions were common, especially among men: 5940 (21.8%) residents were hospitalized (3661 women [18.9%] vs 2279 men [28.9%]; P < .001), 2433 (8.9%) had an emergency department visit (1579 women [8.2%] vs 854 men [10.8%]; P < .001), and 3701 (13.6%) died in an acute care facility (2276 women [11.8%] vs 1425 men [18.1%]; P < .001). Invasive procedures were also common; 2673 residents (9.8%) were attended for life-threatening critical care (1672 women [8.6%] vs 1001 men [12.7%]; P < .001), and 210 (0.8%) received mechanical ventilation (113 women [0.6%] vs 97 men [1.2%]; P < .001). Among the 9844 residents (36.1%) who had a Resident Assessment Instrument Minimum Data Set, version 2.0, completed in the last 30 days of life, 2842 (28.9%) were physically restrained (2002 women [28.3%] vs 840 men [30.4%]; P = .005). More than one-third (9873 [36.2%]) of all residents received an antibiotic (6599 women [34.1%] vs 3264 men [41.4%]; P < .001). In multivariable models, men were more likely to have a transition of care (adjusted odds ratio, 1.41; 95% CI, 1.33-1.49; P < .001) and receive antibiotics (adjusted odds ratio, 1.33; 95% CI, 1.26-1.41; P < .001). Only 3309 residents (12.1%; 2382 women [12.3%] vs 927 men [11.8%]) saw a palliative care physician in the year before death, but those who did experienced greater than 50% lower odds of an end-of-life transition of care (adjusted odds ratio, 0.48; 95% CI, 0.43-0.54); P < .001) and greater than 25% lower odds of receiving antibiotics (adjusted odds ratio, 0.74; 95% CI, 0.68-0.81; P < .001).

CONCLUSIONS AND RELEVANCE

In this study, many nursing home residents with advanced dementia, especially men, received burdensome interventions and antibiotics in their final days of life. These findings appear to emphasize the need for sex-specific analysis in dementia research as well as the expansion of palliative care and end-of-life antimicrobial stewardship in nursing homes.

A generalizable relationship between mortality and time-to-death among breast cancer patients can be explained by tumour dormancy

Background

Women with ER-positive breast cancer may recur as late as 20 years post-diagnosis. The reason for this delayed recurrence is unknown. We studied survival patterns, including time-to-death in 123,705 women with stage I to III invasive breast cancer, enrolled in the SEER database. Among these 76.8% were ER-positive and 23.2% were ER-negative.

Methods

We divided the cohort into ten classes with varying risks of death from breast cancer. The 20-year mortality for women in the highest risk decile 10 was 69% versus 5% for women in the lowest decile 1. The difference in the time-to-death by decile could be explained by a variable α which represents the annual rate of reactivation from tumour dormancy.

Results

The duration of tumour dormancy was much longer, on average, for ER-positive breast cancers than for ER-negative breast cancers. Reactivation from tumour dormancy appears to occur at random and may explain the very long time to cancer recurrence in women with small node-negative ER-positive breast cancers.

Conclusion

The clinical course of women with low-risk ER-positive breast cancer is inherently unpredictable and consequently death is equally as likely to occur at year 3 than at year 20.

Electronic supplementary material

The online version of this article (10.1007/s10549-019-05334-5) contains supplementary material, which is available to authorized users.

The Association Between Insulin Initiation and Adverse Outcomes After Hospital Discharge in Older Adults: a Population-Based Cohort Study

BACKGROUND

Starting insulin therapy in hospitalized patients may be associated with an increase in serious adverse events after discharge.

OBJECTIVE

Determine whether post-discharge risks of death and rehospitalization are higher for older hospitalized patients prescribed new insulin therapy compared with oral hypoglycemic agents (OHAs).

DESIGN

Retrospective population-based cohort study including hospital admissions in Ontario, Canada, between April 1, 2004, and Nov 30, 2013.

PATIENTS

Persons aged 66 and over discharged after a hospitalization and dispensed a prescription for insulin and/or an OHA within 7 days of discharge. We included 104,525 individuals, subcategorized into four mutually exclusive exposure groups based on anti-hyperglycemic drug use in the 7 days post-discharge and the 365 days prior to the index admission.

MAIN MEASURES

Prescriptions at discharge were categorized as new insulin (no insulin before admission), prevalent insulin (prescribed insulin before admission), new OHA(s) (no OHA or insulin before admission), and prevalent OHA (prescribed OHA only before admission) as the referent category. The primary and secondary outcomes were 30-day deaths and emergency department (ED) visits or readmissions respectively.

KEY RESULTS

Of 104,525 patients, 9.2% were initiated on insulin, 4.1% died, and 26.2% had an ED visit or readmission within 30 days of discharge. Deaths occurred in 7.14% of new insulin users, 4.86% of prevalent insulin users, 3.25% of new OHA users, and 3.45% of prevalent OHA users. After adjustment for covariates, new insulin users had a significantly higher risk of death (adjusted hazard ratio (aHR) 1.59, 95% confidence interval (CI) 1.46 to 1.74) and ED visit/readmissions (aHR 1.17, 95% CI 1.12 to 1.22) than prevalent OHA users.

CONCLUSIONS

Initiation of insulin therapy in older hospitalized patients is associated with a higher risk of death and ED visits/readmissions after discharge, highlighting a need for better transitional care of insulin-treated patients.

Denosumab and breast cancer risk in postmenopausal women: a population-based cohort study

BACKGROUND

Denosumab inhibits the receptor activator of nuclear factor κB (RANK) pathway and is used to treat osteoporosis. Emerging evidence suggests RANK-blockade may play a role in mammary tumourigenesis. Thus, we undertook a population-based study of denosumab use and breast cancer risk in a large cohort of postmenopausal women.

METHODS

We included women 67+ years with prior bisphosphonate use who filled a first prescription for denosumab. They were matched on age, date, cumulative prior use of and time since last use of a bisphosphonate to women with no history of denosumab. Cox proportional hazards was used to estimate the hazard ratio (HR) of breast cancer with denosumab use.

RESULTS

A total of 100,368 women were included in the analysis with 1271 incident breast cancer events. Denosumab use was associated with a 13% decreased breast cancer risk (HR = 0.87; 95% CI 0.76-1.00). There was no relationship between increasing number of denosumab doses and breast cancer risk (P-trend = 0.15).

CONCLUSION

These findings suggest a potential protective effect of ever denosumab use on breast cancer risk in a cohort of older women previously treated with bisphosphonates.

Time to death in breast cancer patients as an indicator of treatment response

PURPOSE

To describe the mortality experience of women who die of breast cancer in the 20-year period post-diagnosis using various metrics, including annual mortality rates, Kaplan-Meier survival curves and time-to-death histograms.

METHODS

We generated three visual representations of SEER-based and hospital-based breast cancer patient cohorts using three different metrics of mortality.

RESULTS

The greatest impact of most prognostic factors was on the probability of latent metastases present after treatment, but for some factors the primary impact was on the time to death for those women with metastases.

CONCLUSIONS

The use of time-to-death statistics to display mortality benefits for treated versus untreated women helps facilitate the distinction between treatments which increase the likelihood of cure and treatments that delay cancer growth.

Association of Radiotherapy With Survival in Women Treated for Ductal Carcinoma In Situ With Lumpectomy or Mastectomy

IMPORTANCE

Patients with ductal carcinoma in situ (DCIS) are treated with radiotherapy to reduce their risk of local invasive recurrence after breast-conserving surgery. However, the association of radiotherapy with breast cancer survival in patients with DCIS has not yet been clearly established.

OBJECTIVE

To determine the extent to which radiotherapy is associated with reduced risk of breast cancer mortality in a large cohort of patients treated for DCIS, using a propensity score-based matching approach.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study of women who had first primary DCIS diagnosed between 1998 and 2014 used data from the Surveillance, Epidemiology, and End Results 18 registries database. Information on age and year of diagnosis, ethnicity, income, tumor size, tumor grade, estrogen receptor status, all treatments (surgery and radiation), and outcomes (invasive local recurrence and death from breast cancer) was abstracted for 140 366 women diagnosed with first primary DCIS. Three separate comparisons were performed using 1:1 matching: lumpectomy with radiation vs lumpectomy alone; lumpectomy alone vs mastectomy; and lumpectomy with radiation vs mastectomy.

EXPOSURES

Use of radiotherapy and/or extent of surgery.

MAIN OUTCOMES AND MEASURES

Crude and adjusted 15-year breast cancer-specific mortality.

RESULTS

Of the 140 366 patients with DCIS in the cohort (109 712 [78.2%] white; mean [SD] age, 58.8 [12.3] years), 35 070 (25.0%) were treated with lumpectomy alone, 65 301 (46.5%) were treated with lumpectomy and radiotherapy, and 39 995 (28.5%) were treated with mastectomy. The actuarial 15-year breast cancer mortality rate was 2.33% for patients treated with lumpectomy alone, 1.74% for patients treated with lumpectomy and radiation, and 2.26% for patients treated with mastectomy. The adjusted hazard ratios for death were 0.77 (95% CI, 0.67-0.88) for lumpectomy and radiotherapy vs lumpectomy alone (29 465 propensity-matched pairs), 0.91 (95% CI, 0.78-1.05) for mastectomy alone vs lumpectomy alone (20 832 propensity-matched pairs), and 0.75 (95% CI, 0.65-0.87) for lumpectomy and radiotherapy vs mastectomy (29 865 propensity-matched pairs).

CONCLUSIONS AND RELEVANCE

In patients with DCIS, treatment with lumpectomy and radiotherapy was associated with a significant reduction in breast cancer mortality compared with either lumpectomy alone or mastectomy alone. This suggests that the survival benefit of radiation is likely not due to local control, but rather to systemic effects.

Public reporting of antipsychotic prescribing in nursing homes: population-based interrupted time series analyses

Background

Although sometimes appropriate, antipsychotic medications are associated with increased risk of significant adverse events. In 2014, a series of newspaper articles describing high prescribing rates in nursing homes in Ontario, Canada, garnered substantial interest. Subsequently, an online public reporting initiative with home-level data was launched. We examined the impact of these public reporting interventions on antipsychotic prescribing in nursing homes.

Methods

Time series analysis of all nursing home residents in Ontario, Canada, between 1 October 2013 and 31 March 2016. The primary outcome was the proportion of residents prescribed antipsychotics each month. Balance measures were prescriptions for common alternative sedating agents (benzodiazepines and/or trazodone). We used segmented regression to assess the effects on prescription trends of the newspaper articles and the online home-level public reporting initiative.

Results

We included 120 009 nursing home resident admissions across 636 nursing homes. Following the newspaper articles, the proportion of residents prescribed an antipsychotic decreased by 1.28% (95% CI 1.08% to 1.48%) and continued to decrease at a rate of 0.2% per month (95% CI 0.16% to 0.24%). The online public reporting initiative did not alter this trend. Over 3 years, there was a net absolute reduction in antipsychotic prescribing of 6.0% (95% CI 5.1% to 6.9%). Trends for benzodiazepine prescribing did not change as substantially during the period of observation. Trazodone use has been gradually increasing, but its use did not change abruptly at the time of the mass media report or the public reporting initiative.

Interpretation

The rapid impact of mass media on prescribing suggests both an opportunity to use this approach to invoke change and a warning to ensure that such reporting occurs responsibly.