Indicators of Data Quality at the Cancer Registry Zurich and Zug in Switzerland

The National Cancer Database Conforms to the Standardized Framework for Registry and Data Quality

BACKGROUND

Standardization of procedures for data abstraction by cancer registries is fundamental for cancer surveillance, clinical and policy decision-making, hospital benchmarking, and research efforts. The objective of the current study was to evaluate adherence to the four components (completeness, comparability, timeliness, and validity) defined by Bray and Parkin that determine registries' ability to carry out these activities to the hospital-based National Cancer Database (NCDB).

METHODS

Tbis study used data from U.S. Cancer Statistics, the official federal cancer statistics and joint effort between the Centers for Disease Control and Prevention (CDC) and the National Cancer Institute (NCI), which includes data from National Program of Cancer Registries (NPCR) and Surveillance, Epidemiology, and End Results (SEER) to evaluate NCDB completeness between 2016 and 2020. The study evaluated comparability of case identification and coding procedures. It used Commission on Cancer (CoC) standards from 2022 to assess timeliness and validity.

RESULTS

Completeness was demonstrated with a total of 6,828,507 cases identified within the NCDB, representing 73.7% of all cancer cases nationwide. Comparability was followed using standardized and international guidelines on coding and classification procedures. For timeliness, hospital compliance with timely data submission was 92.7%. Validity criteria for re-abstracting, recording, and reliability procedures across hospitals demonstrated 94.2% compliance. Additionally, data validity was shown by a 99.1% compliance with histologic verification standards, a 93.6% assessment of pathologic synoptic reporting, and a 99.1% internal consistency of staff credentials.

CONCLUSION

The NCDB is characterized by a high level of case completeness and comparability with uniform standards for data collection, and by hospitals with high compliance, timely data submission, and high rates of compliance with validity standards for registry and data quality evaluation.

Quality assessment of a rural population-based cancer registry (PBCR) at Ratnagiri, Maharashtra, India for the years 2017-18

Background

Cancer registries are valuable resources for cancer control and research. To justify their purpose, their data should be of satisfactory quality by being comparable internationally, complete in their coverage, valid in their values and timely in reporting. This study aimed to assess the quality of the Ratnagiri Population Based Cancer Registry's data for the years 2017-18 across the four dimensions of data quality.

Methods

Regarding comparability, the registry procedure was reviewed vis-à-vis the rules they follow for cancer registry operation. We have used four methods for validity: re-abstraction and re-coding, diagnostic criteria methods- like the percentage of microscopically verified (MV%) and of death certificate only (DCO%) cases, missing information like proportion of cases of primary site unknown (PSU%) and internal validity. Semi-quantitative methods were employed for assessing completeness. Timeliness for all years of registry functioning was assessed qualitatively.

Results

The overall accuracy rate of the registry was found to be 91.1% (94.7% for demographic and 88% for tumour details). Mortality to incidence ratios were found to be 0.50 for females and 0.59 for males. MV% was found to be 90.8% for males and 91.5% for females. The average number of sources per case was found to be 1.5. DCO% was found to be 2.7%. PSU% was 7.4%.

Conclusion

We have positive results regarding the data's validity and comparability, but there is scope for improvement concerning completeness. Continuous training of the registry personnel and monitoring of the registry is recommended.

Time-trends and age and stage differences in 5-year relative survival for common cancer types by sex in the canton of Zurich, Switzerland

BACKGROUND

Survival trends help to evaluate the progress made to reduce the burden of cancer. The aim was to estimate the trends in 5-year relative survival of patients diagnosed with breast, prostate, lung, colorectal cancer and skin melanoma in the time periods 1980-1989, 1990-1999, 2000-2009 and 2010-2015 in the Canton of Zurich, Switzerland. Furthermore, we investigated relative survival differences by TNM stage and age group.

METHODS

Data from the Cancer Registry of Zurich was used from 1980 to and including 2015, including incident cases of breast (N = 26,060), prostate (N= 23,858), colorectal (N= 19,305), lung cancer (N= 16,858) and skin melanoma (N= 9780) with follow-up until 31 December 2020. The cohort approach was used to estimate 5-year relative survival.

RESULTS

The 5-year relative survival increased significantly between 1980 and 1989, and 2010 and2015: from 0.70 to 0.89 for breast, from 0.60 to 0.92 for prostate, from 0.09 to 0.23 (men) and from 0.10 to 0.27 (women) for lung, from 0.46 to 0.66 (men) and from 0.48 to 0.68 (women) for colorectal cancer, and from 0.74 to 0.94 (men) and from 0.86 to 0.96 (women) for skin melanoma. Survival for stage IV tumors was considerably lower compared to lower-staged tumors for all cancer types. Furthermore, relative survival was similar for the age groups <80 years but lower for patients aged 80 years and older.

CONCLUSION

The observed increasing trends in survival are encouraging and likely reflect raised awareness around cancer, improved diagnostic methods, and improved treatments. The fact that stage I tumor patients have generally high relative survival reflects the efforts made regarding early detection.

Net survival of women diagnosed with breast tumours: a population-based study in Switzerland

AIMS OF THE STUDY

Although the incidence of breast carcinoma in situ has been increasing, the prognosis of breast carcinoma in situ patients has not been extensively investigated. Thus, we aimed to compare the characteristics of invasive breast tumours based on whether or not they were preceded by a breast carcinoma in situ and to estimate the 5-year net survival of patients diagnosed with different breast tumours.

METHODS

Data from women diagnosed with breast tumours between 2003 and 2016 were used in our analyses. Net survival analyses were performed using inverse probability of censoring weights (nonparametric Pohar Perme estimator). Under certain assumptions, differences in survival between the cancer population and the general population can be considered to be attributable to the cancer diagnosis (NS).

RESULTS

Descriptive observation of tumour characteristics indicated that invasive breast tumours following a breast carcinoma in situ were more frequently detected at an earlier stage and had less missing information in tumour-specific variables, compared to invasive breast tumours not preceded by a breast carcinoma in situ. Breast carcinoma in situ patients had a 5-year net survival of 1.02 (95% CI: 1.01-1.03), whereas patients diagnosed with invasive breast cancer without a recorded breast carcinoma in situ had a 5-year net survival of 0.89 (95% CI: 0.88-0.90). Patients diagnosed first with breast carcinoma in situ and then with invasive breast cancer had a 5-year net survival of 0.92 (95% CI: 0.85-1.01).

CONCLUSION

Invasive breast tumours that were preceded by a breast carcinoma in situ were detected more frequently at an earlier stage, compared to those that were not. The estimated 5-year net survival of patients with breast tumours was good.

Quality indicators: completeness, validity and timeliness of cancer registry data contributing to the European Cancer Information System

Population-based Cancer Registries (PBCRs) are tasked with collecting high-quality data, important for monitoring cancer burden and its trends, planning and evaluating cancer control activities, clinical and epidemiological research and development of health policies. The main indicators to measure data quality are validity, completeness, comparability and timeliness. The aim of this article is to evaluate the quality of PBCRs data collected in the first ENCR-JRC data call, dated 2015.

Methods

All malignant tumours, except skin non-melanoma, and in situ and uncertain behaviour of bladder were obtained from 130 European general PBCRs for patients older than 19 years. Proportion of cases with death certificate only (DCO%), proportion of cases with unknown primary site (PSU%), proportion of microscopically verified cases (MV%), mortality to incidence (M:I) ratio, proportion of cases with unspecified morphology (UM%) and the median of the difference between the registration date and the incidence date were computed by sex, age group, cancer site, period and PBCR.

Results

A total of 28,776,562 cases from 130 PBCRs, operating in 30 European countries were included in the analysis. The quality of incidence data reported by PBCRs has been improving across the study period. Data quality is worse for the oldest age groups and for cancer sites with poor survival. No differences were found between males and females. High variability in data quality was detected across European PBCRs.

Conclusion

the results reported in this paper are to be interpreted as the baseline for monitoring PBCRs data quality indicators in Europe along time.

Operational Feasibility of Hospital-Based Cancer Registries in Low- and Middle-Income Countries: A Systematic Review

Cancer registration is crucial for any country's cancer surveillance and management program. However, there is a lack of systematic evidence on the operational feasibility of hospital-based cancer registries (HBCRs) in low- and middle-income countries (LMICs). We systematically reviewed and described the challenges and prospects of HBCRs in LMICs. We reported the study according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) guidelines. Electronic databases such as MEDLINE, EMBASE, Web of Science, ProQuest, and CINAHL were searched. Peer-reviewed studies published between January 1, 2000 and June 30, 2021 were included. We used thematic analysis to synthesize the findings discussing barriers and enablers of HBCRs. Thirteen studies were eligible for the analysis after eliminating duplicates, screening of title and abstract, and full-text review. The determinants, registry functionality, data management and abstraction, data security, data quality, organizational readiness, and perception of registry staff influence the implementation of HBCRs. In LMICs, many registries lacked functional documentation and data management systems due to a shortage of skilled professionals. However, in many instances, physicians and patients communicated via digital media, which helped obtain accurate data. The HBCR completeness rate was high in Ethiopia, China, Thailand, and Tanzania. Qualification and capacity building of the data managers was linked to the completeness and accuracy of the registry data, which led to sustainability. In addition, a few registries implemented new worksheets to enhance documentation. This review highlights the need for additional digitalization of the cancer registry to improve its functionality, completeness, follow-up, and output. Further, physicians and data managers require regular training to address cancer registry completeness and reduce errors.

Providing Suggested Rules for Multiple Primary Cancer Recording, Coding and Registering in Population-based Cancer Registry

BACKGROUND

Multiple primary cancers (MPC) present many coding difficulties, while a distinction should be made between new cases and those with metastasis and/or extension and recurrence of the primary ones. We aimed to reflect on the experiences and results of data quality control of the East Azerbaijan/Iran Population-Based Cancer Registry and present our suggested rules for reporting, recording and registering multiple primary cancer.

METHODS

Comparability, validity, timeliness, and completeness of data assessment were performed. As a result, we created a consulting team including expert oncologists, pathologists, and gastroenterologists to discuss for multiple primary tumors recording, identifying, coding and registering.

RESULTS

In case of confirmed Blood malignancies with definite BMB results, Brain and/or Bone involvements are always metastatic. In most cases of multiple cancers with the same morphological types, the earlier should be registered as primary tumor. In most of the synchronous multiple cancers, familial cancer syndromes should be considered and rules out. In case of two tumors diagnosed at the same time in colon and rectum, primary site should be detected by T stage or tumor sizes. In case of multiple tumors in Recto-sigmoid, Colon , and Rectum the earlier history of tumor should be considered as primary site. This rule was applied for Female Genital tumors, as earlier site is always the Primary cancer and other tumors should be registered as metastatic sites.  Conclusion: Given the complexity of coding MPCs, we suggested some additional rules for identifying, recording, coding, and registering multiple primary cancers in the context of the EA-PBCR program.

Predicting second breast cancer among women with primary breast cancer using machine learning algorithms, a population-based observational study

Breast cancer survivors often experience recurrence or a second primary cancer. We developed an automated approach to predict the occurrence of any second breast cancer (SBC) using patient-level data and explored the generalizability of the models with an external validation data source. Breast cancer patients from the cancer registry of Zurich, Zug, Schaffhausen, Schwyz (N = 3213; training dataset) and the cancer registry of Ticino (N = 1073; external validation dataset), diagnosed between 2010 and 2018, were used for model training and validation, respectively. Machine learning (ML) methods, namely a feed-forward neural network (ANN), logistic regression, and extreme gradient boosting (XGB) were employed for classification. The best-performing model was selected based on the receiver operating characteristic (ROC) curve. Key characteristics contributing to a high SBC risk were identified. SBC was diagnosed in 6% of all cases. The most important features for SBC prediction were age at incidence, year of birth, stage, and extent of the pathological primary tumor. The ANN model had the highest area under the ROC curve with 0.78 (95% confidence interval [CI] 0.750.82) in the training data and 0.70 (95% CI 0.61-0.79) in the external validation data. Investigating the generalizability of different ML algorithms, we found that the ANN generalized better than the other models on the external validation data. This research is a first step towards the development of an automated tool that could assist clinicians in the identification of women at high risk of developing an SBC and potentially preventing it.

A Bayesian approach to correct the under-count of cancer registry statistics before population-based cancer registry program

Aim

This study aims to correct undercounts in cancer data before initiating a population-based cancer registry program, employing an innovative Bayesian methodology.

Background

Underestimation is a widespread issue in cancer registries within developing countries.

Methods

This secondary study utilized cancer registry data. We employed the Bayesian approach to correct undercounting in cancer data from 2005 to 2010, using the ratio of pathology to population-based data in the Golestan province as the initial value.

Results

The results of this study showed that the lowest percentage of undercounting belonged to Khorasan Razavi province with an average of 21% and the highest percentage belonged to Sistan and Baluchestan province with an average of 38%.The average age-standardized incidence rate (ASR) for all provinces of the country except Golestan province was equal to 105.72 (Confidence interval (CI) 95% 105.35-106.09) per 100,000 and after Bayesian correction was 137.17 (CI 95% 136.74-137.60) per 100,000. In 2010 the amount of ASR before Bayesian correction was 100.28 (CI 95% 124.39-127.09) per 100,000 for women and 136.49 (CI 95% 171.20-174.38) per 100,000 for men. Also, after implementing the Bayesian correction, ASR increased to 125.74 per 100,000 for women and 172.79 per 100,000 for men.

Conclusion

The study demonstrates the effectiveness of the Bayesian approach in correcting undercounting in cancer registries. By utilizing the Bayesian method, the average ASR after Bayesian correction with a 29.74 percent change was 137.17 per 100,000. These corrected estimates provide more accurate information on cancer burden and can contribute to improved public health programs and policy evaluation. Furthermore, this research emphasizes the suitability of the Bayesian method for addressing underestimation in cancer registries. It also underscores its pivotal role in shaping the trajectory of future investigations in this field.

Is Season of Diagnosis a Predictor of Cancer Survival? Results from the Zurich Cancer Registry

In Switzerland, there is a large seasonal variation in sunlight, and vitamin D deficiency is relatively common during winter. The season of diagnosis may be linked to cancer survival via vitamin D status. Using data from the Cancer Registry of Zurich, Zug, Schaffhausen, and Schwyz with more than 171,000 cancer cases registered since 1980, we examined the association of the season of diagnosis with survival for cancers including prostate (ICD10 code C61; International Categorization of Diseases, version 10), breast (C50), colorectal (C18-21), lung (C34), melanoma (C43), and all sites combined. Cox proportional hazards regression models were used to assess the differences in the all-cause mortality by the season of the diagnosis. Winter was used as the reference season. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated for all the cancers combined (excluding nonmelanoma skin cancer) and for prostate (in men), breast (in women), colorectal, lung cancer, and melanomas, separately. A diagnosis in summer and/or autumn was associated with improved survival in all the sites combined for both sexes (men: HR 0.97 [95% CI 0.96-0.99]; women: HR 0.97 [95% CI 0.94-0.99]) and in colorectal (HR 0.91 [95% CI 0.84-0.99]), melanoma (HR 0.81 [95% CI 0.65-1.00]), and breast cancer (HR 0.91 [95% CI 0.94-0.99]) in women. Our study results suggest that a cancer diagnosis in summer and/or autumn is associated with a better prognosis. The improved seasonal survival coincides with the seasonal variation of sun-induced vitamin D, and vitamin D may play a protective and beneficial role in cancer survival.

Active case-finding method improves completeness and accuracy of data reported to the rural Eastern Cape Cancer Registry in South Africa

The quality and accuracy of the data provided by cancer registries has a significant impact on decision making. Over decades, high-income countries have been successful in monitoring their cancer burden because of well-established data abstraction techniques such as digital systems. Conversely, in low- and middle-income countries, sparsely distributed cancer registries, using alternative less costly, but imprecise methods are struggling to capture all cancer cases. A population-based cancer registry in South Africa covering a resource-limited rural population is faced with challenges in case finding yet the quality and accuracy of the data provided has a significant impact on decision making. The objective of this study was to assess data quality using two data quality attributes ‘completeness and accuracy’ and also to determine the benefits of using active and passive case-finding methods for cancer registration in this population. Data used were collected between January 2014 and December 2015 from four hospitals to compare the quality of both active and passive case-finding methods. From all four hospitals during the same period, a first set of data obtained through passive reporting was compared with a second set of data obtained through active case finding. Covering multiple facilities during active case finding can significantly improve quality of data, while passive case finding is challenged by data collection being confined to one specific health facility, only. Better investment in active case finding is recommended in settings with resource-distribution disparities.

Impact of comorbidities at diagnosis on the 10-year colorectal cancer net survival: A population-based study

BACKGROUND

It is established that comorbidities negatively influence colorectal cancer (CRC)-specific survival. Only few studies have used the relative survival (RS) setting to estimate this association, although RS has been proven particularly useful considering the inaccuracy in death certification. This study aimed to investigate the impact of non-cancer comorbidities at CRC diagnosis on net survival, using cancer registry data.

METHODS

We included 1076 CRC patients diagnosed between 2000 and 2001 in the canton of Zurich. The number and severity of comorbidities was expressed using the Charlson Comorbidity Index (CCI). Multiple imputation was performed to account for missing information and 10-year net survival was estimated by modeling the excess hazards of death due to CRC, using flexible parametric models.

RESULTS

After imputation, approximately 35 % of the patients were affected by comorbidities. These appeared to decrease the 10-year net survival; the estimated excess hazard ratio for patients with one mild comorbidity was 2.14 (95 % CI 1.60-2.86), and for patients with one more severe or more than one comorbidity was 2.43 (95 % CI 1.77-3.34), compared to patients without comorbidities.

CONCLUSIONS

Our analysis suggested that non-cancer comorbidities at CRC diagnosis significantly decrease the 10-year net survival. Future studies should estimate net survival of CRC including comorbidities as prognostic factor and use a RS framework to overcome the uncertainty in death certification.

Risk for Invasive Cancers in Women With Breast Cancer In Situ: Results From a Population Not Covered by Organized Mammographic Screening

Background

Even though breast cancer in situ (BCIS) incidence has been increasing, the prognosis of BCIS patients has not been extensively investigated. According to the literature, women with BCIS have a higher risk of developing subsequent invasive breast cancer; conflicting information has been reported regarding their potential risk for a subsequent invasive non-breast cancer.

Methods

Data from 1,082 women, whose first-ever cancer diagnosis was primary BCIS between 2003 and 2015 and were living in the canton of Zurich, were used. Standardized incidence ratios (SIRs) were calculated to compare the risk of an invasive breast or non-breast cancer among women with a primary BCIS with the corresponding risk of the adult female population. SIRs were calculated overall and by patient and tumor characteristics. To investigate potential risk factors (e.g., age at diagnosis, treatment) for a subsequent invasive breast or non-breast cancer we used Cox proportional hazards regression models.

Results

BCIS patients had 6.85 times [95% confidence interval (CI): 5.52-8.41] higher risk of being diagnosed with invasive breast cancer compared to the general population. They additionally faced 1.57 times (95% CI: 1.12-2.12) higher risk of an invasive non-breast cancer. The SIRs were higher for women < 50-years old for both invasive breast and non-breast cancer at BCIS diagnosis. Age ≥ 70-years old at BCIS diagnosis was statistically significantly associated with a subsequent invasive non-breast cancer diagnosis.

Conclusions

BCIS patients had a higher risk of being diagnosed with invasive breast and non-breast cancer compared to the general population. Age 70 years or older at BCIS diagnosis was the only risk factor statistically significantly associated with a subsequent invasive non-breast cancer. Our results support the increased risk for subsequent cancers in BCIS patients reported in the literature. Future studies should establish the risk factors for subsequent cancers, highlight the need for intensive monitoring in this population, and help distinguish BCIS patients who could benefit from systemic therapy to prevent distant cancers.

Geographical variation in malignant and benign/borderline brain and CNS tumor incidence: a comparison between a high-income and a middle-income country

Purpose

There is large variability in reported incidence rates of primary brain/CNS tumors across the world, with mostly higher rates in higher-income countries. The aim was to compare malignant and benign brain/CNS tumor incidence between Zurich (Switzerland), a high-income country, and Georgia, a lower middle-income country.

Methods

For the period March 2009 to February 2012, we extracted the following tumors based on topography according to ICD-O3: C70.0–C72.9, and C75.1 (pituitary gland). Data were categorized into histology groups based on the WHO 2007 histological classification. Age-standardized rates per 100,000 person-years were calculated by subgroups.

Results

We included 1104 and 1476 cases of primary brain/CNS tumors for Zurich and Georgia, respectively. Mean age of patients was significantly lower in Georgia compared to Zurich (50.0 versus 58.3 years). Overall age-standardized incidence rates for malignant and benign brain/CNS tumors were 10.5 (95% CI 9.9–11.0) for Georgia and 23.3 (95% CI 21.9–24.7) for Zurich with a ratio of benign to malignant tumors of 1.656 for Georgia and 1.946 for Zurich. The most frequent histology types were meningiomas in both regions, followed by glioblastomas in Zurich, but pituitary tumors in Georgia.

Conclusion

Age-adjusted incidence rates of brain/CNS tumors were considerably higher in Zurich compared to Georgia, both for benign and malignant tumors, which is in line with other studies reporting higher rates in high-income than in low- and middle-income countries. The frequency distribution may be related to differences in diagnosing techniques and the population age structure.

Electronic supplementary material

The online version of this article (10.1007/s11060-020-03595-5) contains supplementary material, which is available to authorized users.

Magnitude of the Quality Assurance, Quality Control, and Testing in the Shiraz Cohort Heart Study

To determine the conclusive integrity in the Shiraz Cohort Heart Study (SCHS) project, management began quality assurance (QA) and quality control (QC) of the collected data throughout the study end-points. The QA is a focused process that prevents and detects data collection errors and verification of intended requirements in the SCHS. The QC is a subset of QA intended to capture errors in processing data through testing and preventive processes to identify problems, defects, or intended requirements. SCHS involved 10,000 males and females aged 40-70 over a 10-year follow-up period with cardiovascular diseases (CVDs) in the city of Shiraz, Iran. The study measured events and access to preventive care in Shiraz city. The SCHS identified unique barriers to select national study models in developing standardized measures related to variations in ethnicity, religion, cross-cultural considerations, and others. A suggested response to this problem was to develop a mechanism to standardize elements of the questionnaire, study design, and method of administration. This action was based on the geographically normal distribution of the Family Physician Health and Medical Services in Shiraz. Important QA and QC decisions were developed and adopted in the construction of the SCHS and follow-up to ensure conclusive integrity.

The fall and rise of cancer registration in Estonia: The dangers of overzealous application of data protection

BACKGROUND

The population-based Estonian Cancer Registry (ECR) has maintained a database of cancer cases since 1968. Between 2001 and 2007 the ECR was prohibited from linking cancer records to death certificates. In January 2008, the prohibition was lifted, and two years later the ECR was able to begin tracing back unmatched deaths. This paper estimates the effect of the linkage ban on reported cancer incidence and survival.

METHODS

Incident cancers in 2001-2007 were extracted from the ECR database in May 2018 to allow for late registrations. Two datasets were created: one with all incident cases and another without death-certificate-initiated (DCI) cases. Using both datasets, age-standardised incidence rates (ASIR) and their ratios; age-standardised five-year relative survival ratios (ARSR) and excess mortality rate ratios were calculated.

RESULTS

In 2001-2007, 46,535 incident cancers were registered in the ECR. Of them, 2299 (4.9 %) were DCI cases. The inclusion of DCI cases increased the ASIR for overall cancer by 6 % in men and 3 % in women. An increase ≥10 % in ASIR for lung, liver and pancreatic cancer was observed. The effect of accrued DCI cases to the ARSR was minor. Excess mortality in the dataset without DCI cases was 4 % underestimated in men and 3 % in women.

CONCLUSION

Biases in cancer incidence and survival measures generated by the temporary record linkage ban were largely correctable by using trace-back procedures when this became possible. Nevertheless, this type of ban and the arguments put forward to justify it, harm disease registration and register-based research.

Increasing trends in in situ breast cancer incidence in a region with no population-based mammographic screening program: results from Zurich, Switzerland 2003-2014

PURPOSE

Increase in in situ breast cancer (BCIS) incidence has been reported across Europe and the USA. However, little is known about the trends in BCIS incidence in regions without population-based mammographic screening programs. We set out to investigate these trends in Zurich, Switzerland, where only opportunistic mammographic screening exists.

METHODS

Data from 989 women diagnosed with a primary BCIS between 2003 and 2014 were used in our analyses. Age-standardized incidence rates per 100,000 person-years (ASR) were computed per year. Additional analyses by BCIS subtype, by age group at diagnosis and by incidence period were conducted. Incidence trends over time were assessed using joinpoint regression analysis.

RESULTS

The overall BCIS ASR was 10.7 cases per 100,000 person-years with an increasing trend over the study period. A similar trend was observed for the ductal carcinoma in situ (DCIS) ASR, while the lobular carcinoma in situ (LCIS) ASR decreased. Age-specific analyses revealed that the 50-59 year age group had the highest BCIS ASR. The highest increase in BCIS ASR, even though not statistically significant, was observed for the < 40 year age group.

CONCLUSIONS

BCIS ASR increased linearly over a 12-year period. The increase was reflected by an increase in DCIS ASR, whereas LCIS ASR decreased over time. The highest increase in BCIS ASR over the study period was observed for the < 40 year age group, even though not statistically significant. Patient and tumor characteristics of this group that may be associated with BCIS development warrant further investigation.