Adherence to the World Cancer Research Fund/American Institute for Cancer Research cancer prevention recommendations and risk of in situ breast cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort

Background Even though in situ breast cancer (BCIS) accounts for a large proportion of the breast cancers diagnosed, few studies have investigated potential risk factors for BCIS. Their results suggest that some established risk factors for invasive breast cancer have a similar impact on BCIS risk, but large population-based studies on lifestyle factors and BCIS risk are lacking. Thus, we investigated the association between lifestyle and BCIS risk within the European Prospective Investigation into Cancer and Nutrition cohort. Methods Lifestyle was operationalized by a score reflecting the adherence to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention recommendations. The recommendations utilized in these analyses were the ones pertinent to healthy body weight, physical activity, consumption of plant-based foods, energy-dense foods, red and processed meat, and sugary drinks and alcohol, as well as the recommendation on breastfeeding. Cox proportional hazards regression was used to assess the association between lifestyle score and BCIS risk. The results were presented as hazard ratios (HR) and corresponding 95% confidence intervals (CI). Results After an overall median follow-up time of 14.9 years, 1277 BCIS cases were diagnosed. Greater adherence to the WCRF/AICR cancer prevention recommendations was not associated with BCIS risk (HR = 0.98, 95% CI 0.93–1.03; per one unit of increase; multivariable model). An inverse association between the lifestyle score and BCIS risk was observed in study centers, where participants were recruited mainly via mammographic screening and attended additional screening throughout follow-up (HR = 0.85, 95% CI 0.73–0.99), but not in the remaining ones (HR = 0.99, 95% CI 0.94–1.05). Conclusions While we did not observe an overall association between lifestyle and BCIS risk, our results indicate that lifestyle is associated with BCIS risk among women recruited via screening programs and with regular screening participation. This suggests that a true inverse association between lifestyle habits and BCIS risk in the overall cohort may have been masked by a lack of information on screening attendance. The potential inverse association between lifestyle and BCIS risk in our analyses is consistent with the inverse associations between lifestyle scores and breast cancer risk reported from previous studies.

Oncotype DX DCIS use and clinical utility: A SEER population-based study.

e12046 Background: OncotypeDX DCIS is a 12-gene assay designed to predict the 10-year risk of local recurrence and to guide treatment decisions, specifically the benefit of radiation therapy in breast ductal carcinoma in situ (DCIS). The test became available in December 2011 and is not currently recommended by guidelines. The Surveillance, Epidemiology and End Results (SEER) program captures cancer data at the population-level and has been conducting annual linkages with Genomic Health Clinical Laboratory, the only lab performing the test, to identify patients receiving the test. Methods: SEER cases diagnosed with in situ breast cancer (DCIS or papillary in situ) between 2011-2015 were included in the analysis. SEER data on patient demographics, tumor characteristics, and treatments were combined with linkage variables for OncotypeDX DCIS tests reported by Genomic Health. Logistic regression was used to identify which patient related factors were associated with having received the test and to evaluate the relationship between test generated risk categories and treatments. Results: Of the 68,826 in situ breast cancer cases, 2,155 were linked to DCIS test data. Test utilization increased from < 1% to 5.3% for patients diagnosed in 2011 vs. 2015. Patients were less likely to receive the test if they had larger and higher-grade tumors, were divorced, had Medicaid insurance, and were in the lowest socioeconomic status tertile. The majority of patients (68%) were at low risk, 17% intermediate, and 15% in the high risk group. Patients at intermediate or high risk were more likely to receive radiation (OR = 2.4, 95% CI: 1.8-3.2 and OR = 3, 95% CI: 2.3,4.1, respectively) than the low risk group. High risk patients were more likely than low risk patients to receive chemotherapy (OR = 4.3, 95% CI: 1.2, 14.4) and to undergo mastectomy than lumpectomy (OR = 1.47, 95% CI: 1.12-1.93). Conclusions: Clinical adoption of the OncotypeDX DCIS test has been slow. The association between multiple demographic factors and receiving the test indicated disparities in the US population. Clinical factors also influenced whether patients received the test. OncotypeDX DCIS results appeared to guide clinical decisions.