Survival, treatment patterns, and costs of HER2+ metastatic breast cancer patients in Ontario between 2005 to 2020

BACKGROUND

To enable the integration of novel therapies, it is critical to understand current long-term outcomes in HER2-positive metastatic breast cancer (mBC), including survival, treatment patterns, and costs. We sought to define these outcomes among patients with mBC in Ontario.

METHODS

We conducted a retrospective population-level study in Ontario women diagnosed with breast cancer of any stage between January 1, 2005 and December 31, 2019, with follow-up until December 31, 2020. HER2-positivity was based on receipt of a HER2-targeted therapy (HER2-TT) in the first line (1L) metastatic setting. Administrative databases at ICES were used to assess outcomes.

RESULTS

In Ontario, 2557 patients were diagnosed with mBC and received a HER2-TT, and of these 1606 were diagnosed with early-stage (stage I-III) that became metastatic (recurrent), while 951 were diagnosed with late stage/de novo mBC (stage IV). The average age of all patients was 54.8 years ± 12.7 years. Treatment regimens that included pertuzumab and trastuzumab (cohort name: pert_tras) were the most frequently used HER2-TT for 1L mBC (51.4%), while T-DM1 was the most frequent therapy (87.5%) in second line (2L). The median overall survival (mOS) from initiation of 1L pert_tras was not reached, whereas mOS from initiation of T-DM1 in 2L was 18.7 months. The overall mean cost per patient on pert_tras during 1L was $267,282. The main cost drivers were the cost of systemic therapy, followed by cancer clinic visits, with a mean cost per patient at $158,961 and $73,882, respectively.

CONCLUSION

The baseline characteristics and treatment patterns for patients who received HER2-TT in our study align with previously reported results. However, the mOS observed for 2L T-DM1 was shorter than that found in pivotal, clinical trial literature. As expected, anti-cancer systemic therapy costs were the main contributor to the over quarter-million dollar mean cost per patient on pert_tras in 1L.

Use of a vaginal CO2 laser for the management of genitourinary syndrome of menopause in gynecological cancer survivors: a systematic review

Genitourinary syndrome of menopause (GSM) may arise from the hypoestrogenism caused by ovarian function destruction following gynecological cancer treatments. GSM may also be present in menopausal women and its symptoms might be exacerbated by cancer treatments. Historically, patients with hormone-dependent gynecological cancer and physicians have been less comfortable using vaginal estrogen due to fear of recurrence. CO₂ vaginal laser therapies have demonstrated efficacy as a non-hormonal alternative for GSM treatment in healthy menopausal patients. The objective of this study was to evaluate the data on the effect of a CO₂ vaginal laser for the management of GSM in gynecological cancer patients. Databases searched included MEDLINE, Embase, PubMed, Cochrane and Google Scholar. Selected studies assessed use of a CO₂ vaginal laser in gynecological cancer patients with GSM. A total of 269 studies were retrieved. Four studies met the inclusion criteria. Each study followed a different type of CO₂ vaginal laser protocol for the management of GSM in gynecological cancer patients. There are no randomized controlled trials that assess the use of a CO₂ vaginal laser in gynecologic cancer patients. The number of published gynecological cancer patients treated with a CO₂ laser for the management of GSM is extremely limited (N < 100). There is a lack of literature on the impact and safety of vaginal CO₂ laser use to manage GSM in gynecologic cancer patients.

Association between global longitudinal strain and cardiopulmonary fitness in patients with breast cancer

Background

Anthracycline and trastuzumab therapies improve survival in the cancer population, but are limited by treatment induced cardiotoxicity. Echocardiography derived global longitudinal strain (GLS) permits more sensitive detection of cardiotoxicity than left ventricular ejection fraction (LVEF). However, the clinical implication of a reduction in GLS in cancer survivors is unknown.

Purpose

To define the association between GLS and cardiopulmonary fitness in women with breast cancer immediately post cancer therapy.

Methods

Women with HER2+ early stage breast cancer (EBC, Stage I-III) receiving anthracyclines followed by trastuzumab were recruited prospectively and followed between January 2015 and December 2019 with echocardiography during therapy. Left ventricular peak systolic GLS (GE EchoPAC, 3 apical views) and 3D-LVEF were measured prior to anthracyclines, and after completion of trastuzumab at 12 months. Exercise capacity was measured using a supine bicycle cardiopulmonary exercise test. Results of exercise testing at end of treatment were compared between patients with and without reduced GLS (absolute value ≤18% vs &gt;18%) at the end of therapy.

Results

Amongst 128 women, 43 (34%) had a GLS ≤18% at the end of trastuzumab therapy. Baseline patient demographics including tumor characteristics and cardiac risk factors were similar between those with normal and abnormal GLS. During treatment 33 (25.8%) participants developed cardiotoxicity defined by the CREC criteria based on 3D-LVEF. Significant baseline (pre-cancer treatment) differences were found between groups for GLS (GLS 21.2±1.8 vs 19.6±2.2, p&lt;0.001) and 3D LVEF (61.8±3.5 vs 60.2±3.7%, p=0.02) for those with GLS &gt;18% and GLS ≤18% respectively at the completion of trastuzumab. Compared to those with GLS &gt;18% those with GLS ≤18% had lower VO2peak (17.4±3.8 mL.kg-1.min-1 versus 20.2±4.9 mL.kg-1.min-1, p=0.001) despite similar effort (respiratory exchange ratio 1.14 versus 1.12, p=0.30). GLS following therapy (β coefficient: −0.596, SE 0.255; p=0.02) and age (β coefficient: −0.115, SE 0.057; p=0.047) were the only parameters associated with VO2peak after adjusting for relevant confounding factors.

Conclusion

A significant proportion of women receiving cancer therapy for HER2+ EBC had reduced GLS at end of treatment. Abnormal GLS at the end of cancer treatment was associated with lower VO2peak. Reduced VO2peak is strongly associated with late-occurring cardiovascular events and should prompt closer cardiac monitoring, cardiac risk factor management, and referral to exercise rehabilitation programs.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Canadian Institute of Health Research

Real-world use of trifluridine/tipiracil for patients with metastatic colorectal cancer in Canada

Background

Outcomes for patients with metastatic colorectal cancer (mcrc) are improving with the introduction of new treatments. Treatment for patients who are still fit after failure of all available therapies represents a significant unmet need. In the present study, we analyzed real-world treatment patterns for patients enrolled in Health Canada's trifluridine/tipiracil (ftd/tpi) Special Access Program (sap) and Taiho Pharma Canada's Patient Support Program (psp).

Methods

Demographic information and clinical treatment data were collected from adults with mcrc who were previously treated with, or were not candidates for, available therapies and who were enrolled in the sap and psp. For all patients, ftd/tpi treatment status, discontinuation reasons, and prior therapies were examined.

Results

The analysis included 717 Canadian patients enrolled in the ftd/tpi sap and psp from September 2017 to October 2018. In that cohort, 59.7% were men, median age was 65 years, and median duration of therapy was 77 days (25%-75% interquartile range: 43-106 days). Of treated patients, 67.1% maintained the same dose for the duration of therapy; 28.0% had a dose reduction.On multivariable analysis, duration of therapy was not influenced by sex, age, province, RAS mutation status, or prior therapies. However, prior oxaliplatin-based chemotherapy (capox or folfox) appeared to be associated with higher rates of discontinuation because of death or disease progression.

Conclusions

In advanced mcrc, ftd/tpi is a well-tolerated therapy. The large number of patients enrolled in the access programs within a short period of time is reflective of major clinical need in this area, with many patients being eligible and interested in pursuing treatment in the refractory setting.

An international survey of healthcare providers' knowledge of cardiac complications of cancer treatments

Background

Cardio-oncology is a young sub-specialty that addresses the needs of cancer patients at risk of, or who have experienced cancer therapy related cardiac dysfunction (CTRCD). This study assessed clinicians' understanding of cardio-oncology, opinions towards current practice, and approach to diagnosing and managing CTRCD.

Methods

A 45-question survey was administered online via Survey Monkey and WeChat to health care providers (HCPs) comprising of cardiologists, oncologists, and others from September 2017 to March 2018. Implementation of the survey followed a modified Dillman's Total Design Method.

Results

In total, 160 responses were collected from 22 countries; majority were from cardiologists (53.8%) and oncologists (32.5%). The remaining 13.7% identified themselves as "others," including general internists, cardio-oncologists, pediatric oncologists, radiation oncologists, cardiac rehabilitation therapists, nurse practitioners, research students, and pharmacists. In the setting of metastatic cancer, there was a difference in risk tolerance for cardiotoxicity between subspecialties. In this case, more cardiologists (36.7%) accepted a 5-10% risk of cardiotoxicity compared to oncologists (20.0%). Majority of cardiologists felt that cardiotoxicity should be monitored, even in asymptomatic cancer patients (55.8%). Only 12% of oncologists selected this response. In contrast, 50.0% of oncologists reported that cardiologists should be involved only when patients develop cardiotoxicity. In comparison, 6.5% of cardiologists selected this response. Majority of cardiologists stated that cardio-oncology clinics would significantly improve cancer patients' prognosis (88.3%); only 45.8% of oncologists shared this opinion. Of all respondents, 66.9% stated they were familiar with a variety of international guidelines for managing cardiotoxicity. Of all oncologists, 65.3% indicated that they referred to these guidelines for clinical decision making.

Conclusions

Despite the growth of cardio-oncology clinics, there are significant knowledge gaps regarding prevention and treatment strategies for CTRCD among health care providers. Knowledge translation from guidelines and collaboration between cardiologists and oncologists are needed to improve cardiovascular outcomes of cancer patients.

Overcoming endocrine resistance in hormone receptor-positive breast cancer

Endocrine therapy, a major modality in the treatment of hormone receptor (hr)-positive breast cancer (bca), has improved outcomes in metastatic and nonmetastatic disease. However, a limiting factor to the use of endocrine therapy in bca is resistance resulting from the development of escape pathways that promote the survival of cancer cells despite estrogen receptor (er)-targeted therapy. The resistance pathways involve extensive cross-talk between er and receptor tyrosine kinase growth factors [epidermal growth factor receptor, human epidermal growth factor receptor 2 (her2), and insulin-like growth factor 1 receptor] and their downstream signalling pathways-most notably pi3k/akt/mtor and mapk. In some cases, resistance develops as a result of genetic or epigenetic alterations in various components of the signalling pathways, such as overexpression of her2 and erα co-activators, aberrant expression of cell-cycle regulators, and PIK3CA mutations. By combining endocrine therapy with various molecularly targeted agents and signal transduction inhibitors, some success has been achieved in overcoming and modulating endocrine resistance in hr-positive bca. Established strategies include selective er downregulators, anti-her2 agents, mtor (mechanistic target of rapamycin) inhibitors, and inhibitors of cyclin-dependent kinases 4 and 6. Inhibitors of pi3ka are not currently a treatment option for women with hr-positive bca outside the context of clinical trial. Ongoing clinical trials are exploring more agents that could be combined with endocrine therapy, and biomarkers that would help to guide decision-making and maximize clinical efficacy. In this review article, we address current treatment strategies for endocrine resistance, and we highlight future therapeutic targets in the endocrine pathway of bca.

Hormone receptor-positive, HER2-negative metastatic breast cancer: redrawing the lines

Estrogen receptor modulators and estrogen deprivation have become standards of care for hormone receptor-positive metastatic breast cancer. However, after traditional first-line endocrine monotherapy treatment, the disease typically progresses despite the initial high rate of clinical benefit. Multiple studies have aimed at optimizing treatment strategies to improve upon clinical benefit beyond the traditional single-agent endocrine treatment. With the availability of new data and novel therapies, the clinical practice challenge becomes how best to define the optimal treatment sequence to maximize clinical benefit. In this review, we present treatment options clinically relevant to the management of hormone-positive, her2-negative metastatic breast cancer, and we propose a treatment algorithm based on the current literature.

Abstract P5-17-03: Breast cancer in young women in Canada: A needs assessment

Objective: A Needs Assessment was conducted by Rethink Breast Cancer to assess age-related differences in experiences for breast cancer patients. This was the first national survey to identify the needs and current gaps in care for younger breast cancer patients. The report, published in March 2013, provided critical evidence-based information and benchmarks to stakeholders on the associated challenges. The following data supplements the main findings presented at the 2013 SABCS by providing a descriptive overview of the differences in breast cancer experiences between younger (≤45 years of age) and older (&gt;45 years of age) women.

Methods: From June to October 2011, an online bilingual (English and French) quantitative survey was open to Canadian women who had a diagnosis of breast cancer (initial or recurrence) in the prior 6 years. The survey focused on their pre-diagnosis, diagnosis, treatment, and post-treatment experiences. 574 women responded to the survey: 372 (65%) aged ≤45 years and 202 aged &gt;45 years. The differences in responses between the younger and older respondents was analyzed using the Pearson's Chi-Square test (α = 0.05).

Results: Finding a lump (64.3 vs 39.6%; p &lt;.01) and experiencing pain or discomfort in the breast (24.5 vs 14.4%; p &lt;.01) were significantly more likely to cause concerns in younger women. Older women were significantly more likely to be concerned by results from a screening test/mammogram (45.0 vs 8.1%; p &lt;.01). It is plausible that younger women do not receive mammograms as often as their older counterparts. Of the 319 women that found a lump, self-examination (38.6%) was the most frequent method of discovery. However, this was significantly more likely among older rather than younger women (51.3 vs 34.3%; p = 0.02). Follow-up appointments for future reassessment were significantly more likely to be scheduled with younger rather than older women (15.1 vs 5.0%; p = 0.02). With respect to treatment, younger women were significantly more likely than older women to be recommended chemotherapy (81.7 vs 67.3%; p &lt;.01), targeted therapy (21.0 vs 10.9%; p &lt;.01), bilateral mastectomy (17.2 vs 8.9%; p &lt;.01), breast reconstruction (30.9 vs 14.4%; p &lt;.01), node dissection (37.9 vs 23.3%; p &lt;.01), oophorectomy (10.8 vs 5.0%; p = 0.02), and hysterectomy (7.8 vs 2.0%; p &lt;.01). Transitioning from regular to occasional monitoring by a healthcare team was reported to be very or somewhat difficult (59.1 vs 41.8%; p &lt;.01) for younger instead of older women, while older women were significantly more likely to report little to no difficulty with this transition (58.2 vs 40.9%; p &lt;.01).

Conclusions: The Needs Assessment demonstrated significant age-related differences in almost all aspects of breast cancer care, including during pre-diagnosis, treatment, and post-treatment. Differences such as greater recommendations for more aggressive treatments and difficulty in care transitions may lead to challenges being faced by younger women relative to their older counterparts. Tools such as checklists and guidelines may assist healthcare teams in meeting the needs of younger women. Future studies are warranted to assess the impact of such tools in helping improve patient education, advocacy, and support programs for this population.

Citation Format: DeCoteau MJ, Mercado MG, Ginsberg S, Dhir V, Brezden-Masley C. Breast cancer in young women in Canada: A needs assessment [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-17-03.

Cancer Screening Recommendations for Solid Organ Transplant Recipients: A Systematic Review of Clinical Practice Guidelines

Solid organ transplant recipients (SOTRs) are at increased risk of developing and dying from cancer. However, controversies exist around cancer screening in this population owing to reduced life expectancy and competing causes of death. This systematic review assesses the availability, quality and consistency of cancer screening recommendations in clinical practice guidelines (CPGs). We systematically searched bibliographic databases and gray literature to identify CPGs and assessed their quality using AGREE II. Recommendations were extracted along with their supporting evidence. Thirteen guidelines were included in the review. CPGs for kidney recipients were the most frequent source of screening recommendations, and recommendations for skin cancer screening were most frequently presented. Some screening recommendations differed from those for the general population, based on literature demonstrating higher cancer incidence among SOTRs versus direct evidence of screening effectiveness. Relevant stakeholders such as oncology specialists, primary care providers and public health experts were not involved in the formulation of the screening recommendations. In conclusion, although several guidelines make recommendations for cancer screening in SOTRs, the availability of cancer screening recommendations varied considerably by transplanted organ. More studies are required to inform cancer screening recommendations in SOTRs, and guideline development should involve transplant patients, oncologists and cancer screening specialists.

Abstract P2-02-12: Association of inflammatory and tumor markers with circulating tumor cells in metastatic breast cancer

Background: Circulating tumor cells (CTCs) are associated with prognosis in metastatic breast cancer (BC). We evaluated the association of inflammatory/tumor markers and CTCs in women with progressing metastatic breast cancer prior to commencing a new line of systemic therapy.

Methods: From February 2013 to April 2015, 96 patients with metastatic BC about to start a new treatment (due to progression), without current diabetes or use of anti-inflammatory agents, were recruited from four Ontario cancer hospitals. Women provided fasting blood for inflammatory and tumor markers and CTC measurement; CTCs were assayed within 72 hours of collection using CellSearch. Blood was frozen at -80C until assays were performed in a single batch (C-reactive protein (CRP), IL-6, PAI-1, Ca15-3, Ca125, VEGF, TNFa). Associations of CTCs with blood factors were evaluated using Pearson correlation coefficients after transforming the variables to normality. For CTCs the transformation log(x+0.5) was used. Associations with categorical variables were tested using one-way analysis of variance. P values &lt;0.05 were significant.

Results: Median age of patients was 60.5 years, 87 (90.6%) were post-menopausal, 83 (86.5%) had hormone receptor positive BC, 16 (16.7%) HER2 positive BC, 10 (10.4%) triple negative; 75 (78.1%) grade II/III. At the time of CTC measurement, bone, lung, liver and brain metastases were present in 79%, 44%, 40% and 6% of patients respectively, with 54%, 37%, 35% and 3% having progression at these sites respectively. PAI-1 and CA15-3 exceeded the limit of the assay in 11 and 5 cases respectively (the upper limit of the assay was used in the analysis). 33.4% of patients were starting first line therapy, 25% second line and 16.7% third line. CTC counts (per 7.5cc) ranged from 0 to 1238 (median 2, geometric mean 3.63); none were detected in 29 (30.2%) patients, 1 to 4 in 25 (26%) and 5 or more in 42 (43.8%) patients. CTCs were not associated with age, estrogen receptor, progesterone receptor, HER2, line of treatment, lymph-vascular invasion or tumor grade. Compared to metastatic disease at other sites, CTCs were higher in the presence of bone (p=0.027) and liver metastases (p=0.002) and with progressing bone (p=0.018) and liver (p=0.012) metastases. CTCs were significantly associated with CRP (R =0.25, p=0.014), IL-6 (R=0.31, p=0.002), PAI-1 (R=0.31, p=0.002), Ca15-3 (R=0.44, p=&lt;0.0001) and Ca 125 (R=0.21, p=0.04) but not with VEGF and TNFa (R = 0.11, p= 0.29 and R = 0.16, p=0.11, respectively).

Conclusion: CTCs were associated with bone and liver metastases and with higher levels of inflammatory and tumor markers, potentially reflecting tumor burden. Additional inflammatory marker assays are underway. Future studies are warranted to confirm these findings.

Citation Format: Lohmann AE, Chang M, Dowling RJO, Ennis M, Amir E, Elser C, Brezden-Masley C, Vandenberg T, Lee E, Fazae K, Stambolic V, Goodwin PJ. Association of inflammatory and tumor markers with circulating tumor cells in metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-12.

Abstract P2-02-09: Obesity associated factors are inversely associated with circulating tumor cells in metastatic breast cancer

Background: Elevated levels of circulating tumor cells (CTCs) are associated with adverse outcomes in metastatic breast cancer (BC). However, relationships between CTCs and various patient-related factors that may impact outcome remain undefined. Consequently, associations of CTC counts with obesity and metabolic factors were evaluated in order to gain insight into potential interactions between patient physiology and disease burden. We hypothesized that obesity and associated metabolic factors would be associated with higher CTC counts.

Methods: Non-diabetic women with metastatic BC beginning a new line of treatment due to progressive disease were recruited from four Ontario cancer hospitals between February 2013 and April 2015. Patients provided blood for CTC analysis, which was completed within 72 hours of collection using the Janssen CellSearch platform. Fasting serum was also collected for assessment of metabolic factors including glucose (mmol/L), insulin (pmol/L), leptin (ng/mL) and adiponectin (ng/mL). Associations of CTC counts with these factors, as well as anthropometric measurements (height (cm), weight (kg), BMI (kg/m2)) were evaluated using Pearson correlation coefficients after transforming the variables involved to normality. For CTC counts, the log transformation with half integer correction was used.

Results: 96 patients with a median age of 60.5 years completed the study. Most were post-menopausal (87, 90.6%) and exhibited grade II/III tumors (75, 78.1%). The majority of patients had hormone receptor positive disease (83, 86.5%), but 16.7% (16) were HER2 positive and 10.4% (10) were triple negative. The number of CTCs observed ranged from 0 to 1238 (median 2, geometric mean 3.63). No CTCs were detected in 29 patients (30.2%), whereas 25 patients (26 %) exhibited counts of 1 to 4 CTCs and 42 (43.8%) had 5 or more CTCs. CTCs were not significantly associated with tumor characteristics including ER/PgR, HER2, grade, stage (T/N) or lymphovascular invasion. The number of CTCs inversely correlated with BMI (r=-0.26, p=0.01), leptin (r=-0.29, p=0.004), and leptin-adiponectin ratio (r=-0.3, p=0.004). A similar trend that approached significance was noted for body weight (r=-0.19, p=0.07), insulin (r=-0.19, p=0.06) and homeostatic model assessment (HOMA, an estimate of insulin resistance, r=-0.2, p=0.055). Conversely, adiponectin (r=0.18, p=0.07) and height (r=0.18, p=0.07) were positively associated with CTC counts in correlations that neared significance. No associations were observed for age (r=0.09, p=0.4) or glucose (r=-0.09, p=0.4).

Conclusions: Obesity associated metabolic factors including weight, BMI, insulin, HOMA and leptin were inversely associated (and adiponectin and height positively associated) with CTC counts. These patterns are consistent with weight loss and/or cachexia in women with elevated CTC counts who have higher disease burden. Additional analyses are underway to further characterize these associations and include assessment of serum albumin, free fatty acids, creatine kinase and hepcidin.

Citation Format: Dowling RJO, Chang MC, Lohmann AE, Ennis M, Amir E, Elser C, Brezden-Masley C, Vandenberg T, Lee E, Fazaee K, Stambolic V, Goodwin PJ. Obesity associated factors are inversely associated with circulating tumor cells in metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-09.

P5-08-04: Mammographic Microcalcifications and Breast Cancer Tumorigenesis: A Radiologic-Pathologic Analysis

Background

Microcalcifications (MCs) are tiny deposits of calcium in breast soft tissue. They serve as key diagnostic radiological features for localization of malignancy. Approximately 30% of early invasive breast cancers have fine, granular MCs detectable on mammography; however, their role in breast cancer tumorigenesis is currently unknown. The purpose of this study was to investigate the relationship between mammographic MCs and breast cancer pathology.

Methods: A retrospective chart review was performed for 882 women treated for breast cancer between 2000–2010 at St. Michael's Hospital. Demographic information (age and menopausal status), tumor pathology (size, histology, grade, nodal status and lymphovascular invasion), hormonal status (ER and PR), HER-2 overexpression and presence of MCs were collected for breast cancer patients. Chi-square tests were performed for categorical variables and t-tests were performed for continuous variables. All tests were two-sided and p-values less than 0.05 were considered statistically significant.

Results: A total of 826 patient charts were included; 56 (6.4%) patients had metastatic carcinoma and were excluded from analysis. Only 37.0% (326/882) of the patients presented with mammographic MCs. Patients were more likely to have MCs if they were HER-2 positive (51%) as opposed to being HER-2 negative (33.4%) (p=0.001). There was a significant association between MCs and being perimenopausal with a mean age of 50 (65.2%) (p=0.012). Patients with invasive ductal carcinomas (39.7%) were more likely to present with MCs than were patients with other tumor histology (p=0.001). There was a positive correlation between MCs and tumor grade (p=0.051), with grade III tumors (41.85%) presenting with the most MCs, followed by grade II (37.95%) and grade I (29.8%). There was no significant association between mean age, mean tumor size, ER and PR status with the presence of MCs.

Conclusion: This is the largest study that suggests the appearance of MCs on mammograms is strongly associated with HER-2 overexpression, invasive ductal carcinoma and perimenopausal status. Since HER-2 is implicated in mediating aggressive tumor growth and metastasis, future studies should investigate the molecular pathways underlying HER-2 overexpression and MC development. This would help better understand the role of MCs in breast cancer tumorigenesis.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-08-04.

Abstract P5-15-05: Applicability of Breast Cancer Guidelines and Knowledge Translation in a Community Oncology Setting

Background: The quality of a guideline may impact adherence to that guideline. Cancer Care Ontario (CCO) produces guidelines to help manage all stages of disease. CCO's staging and follow-up guideline suggests patients (pts) with stage I breast cancer require no further staging investigations, bone scan for stage II disease, and for stage III disease in addition to bone scan, chest and abdominal imaging. The guideline on bisphosphonate (BP) use in metastatic breast cancer pts indicates that all pts with bone metastases should be offered a BP. We assessed the efficacy of knowledge translation of these guidelines at a community oncology centre by correlating rate of adherence with the quality of the guideline as scored using the Appraisal of Guidelines for Research and Evaluation (AGREE) Instrument.

Methods: The quality of 2 breast cancer guidelines from CCO were assessed using the AGREE instrument. Two cohort studies of breast cancer pts seen were then conducted to evaluate the adherence to these guidelines. Specifically, staging investigations ordered on pts seen in our multidisciplinary clinic between January 2009 and April 2010 were recorded and correlated to pathological stage of disease. Our second cohort study reviewed breast cancer pts with bone metastases who died between 1999 and 2009, and initiation of a BP was recorded in order to determine adherence to the second guideline.

Results: Inadequate adherence was identified and correlated with low applicability scores for these two guidelines (58% and 33% respectively). Only 68 pts (61%) with bone metastases received BP for treatment between 1999 to 2009. 129 pts (56%) underwent unnecessary staging investigations.

Discussions: Non-chemotherapy breast cancer guidelines by CCO scored low in the field of applicability; this was confirmed by two retrospective cohort studies. Improvement in knowledge translation strategies are needed to improve adherence to practice guidelines set out by this national organization.

Long-term results of concurrent gemcitabine (G) and radiotherapy (GRT) for locally advanced (LA) or high-risk resected (R) pancreatic cancer

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Background: G is active against pancreatic carcinoma and is a potent radiosensitizer. We present extended follow up data from a phase I/II study of patients treated with combination GRT. Methods: Eligible patients had either LA or high-risk resected [R] pancreatic cancer [positive nodes or positive margin]. 28 were enrolled in a Phase I study of increasing doses of radiotherapy (35 Gy [n = 7]/43.75 Gy [n = 11]/52.5 Gy [n = 10] given over 4, 5 or 6 weeks, respectively in 1.75 Gy fractions) concurrently with 40 mg/m2 gemcitabine biweekly. Subsequently 35 were treated with induction gemcitabine (G) 1000 mg/m2 7/8 weeks followed by concurrent bi-weekly gemcitabine (40 mg/m2) with 52.5 Gy (30 fractions of 1.75 Gy over 6 weeks). In total there were 63 patients (31 LA and 32 R) treated between March 1999–July 2001. Results: In the LA population the best response observed was CR - 1, PR - 2, SD - 10, PD - 10. GRT was not delivered to 8 patients due to progression on G alone (n = 5) or patient request (n = 3). By intent to treat analysis, the median survival in LA disease was 15.1 months and the 2 year survival was 19%. In the resected population the median time to progression was 14.3 months, the median survival was 17.9 months and the 5 year survival was 19%. The treatment was generally well tolerated during both the induction G and the GRT ( Table ). Conclusion: Survival for both LA and HR patients with this concurrent gemcitabine radiotherapy regimen is promising and warrants further investigation.

[Table: see text]

No significant financial relationships to disclose.

Autoimmune hypothyroidism protects against breast cancer development in the elderly

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Background: An association between breast cancer and autoimmune hypothyroidism has been suggested. While a biological role for thyroid hormone in breast tumorigenesis has been demonstrated in vitro, epidemiological evidence is lacking. Methods: A retrospective, population-based cohort study was conducted to examine the risk of postmenopausal breast cancer (BRCA) in women with or without autoimmune hypothyroidism, identified on the basis of prescriptions for levothyroxine (LT4). Administrative health records were used to capture information on all women aged 66 and older living in Ontario, Canada at baseline (April 1, 1993 to March 31, 1996) and during a 10-year follow up. Propensity scores were used to create a matched cohort of LT4 and non-LT4 users. Cox proportional hazards modeling was used to evaluate the impact of LT4 use on the 5-year incidence of BRCA and benign breast disease, and on all-cause mortality rates among women diagnosed with breast cancer during follow-up. Results: LT4 users (N=89,093) and non-LT4 users (N=89,093) were well-matched with respect to baseline sociodemographics, estrogen use, comorbidity, and health care utilization, including the likelihood of receiving mammography or a breast biopsy. The 5-year incidence of BRCA was 0.86% in LT4 users compared to 0.97% in non-LT4 users (p=0.002). Adjustment for baseline characteristics did not alter these results (hazard ratio [HR] 0.86; 95% confidence interval [CI] 0.77–0.95; p= 0.004). Among women who developed BRCA, all cause mortality was significantly lower in LT4 users than in non-users (43.9% vs. 56.1%; adjusted HR 0.82; 95% CI 0.70–0.96; p= 0.01). The incidence of benign breast disease did not vary between groups. Conclusions: Elderly women with autoimmune hypothyroidism appeared to have a protective advantage in the incidence of BRCA and in mortality following a breast cancer diagnosis. These results suggest a biological role for thyroid hormone in the development of breast cancer, with a modulating effect of treated autoimmune hypothyroidism in promoting a less aggressive disease course. Further studies exploring the effect of thyroid hormone in breast cancer development are needed and may uncover novel therapeutic targets in the management of breast cancer in the future.

No significant financial relationships to disclose.