Improved Outcomes for Breast Cancer in Contemporary Era

Canadian researchers report on relapse risk and outcomes in women diagnosed with breast cancer in the modern versus historic treatment eras

medwireNews: The risk of relapse is reduced and outcomes are improved in a contemporary cohort of women with breast cancer compared with a historic cohort, a retrospective analysis shows.

“The greatest improvements in outcomes were achieved in the [breast cancer] subtypes known to be more aggressive, namely the [human Epidermal growth factor receptor 2 (HER2)]-positive and [estrogen receptor (ER)]-negative/HER2-negative patients”, observe Karen Gelmon, from Vancouver Cancer Centre in British Columbia, Canada, and colleagues.

The researchers compared the hazard rate of relapse (HRR) for 3589 patients with stage I to III breast cancer diagnosed between July 2004 and December 2008 (contemporary cohort) with that of 3589 patients matched for disease stage, grade, and ER and HER2 status who were diagnosed between January 1986 and December 1992 (historic cohort). The median follow-up for the contemporary and historic cohorts was 6.1 and 15.5 years, respectively.

Participants in the contemporary cohort were 50% less likely to experience disease relapse at each yearly interval compared with those in the historic cohort for the first 7 years of follow-up. The HRR was lower in the contemporary versus the historic cohorts irrespective of disease stage and tumour grade.

When the cohorts were stratified by ER status, patients with ER-negative tumours had a higher HRR than those with ER-positive cancer in the initial 4 years of follow-up, after which the HRRs for ER-negative and ER-positive patients crossed, indicating late relapses in the latter.

This pattern was observed in both the contemporary and historic cohorts, but the risk of relapse was reduced by approximately half for ER-negative patients in the contemporary cohort compared with those in the historic cohort, and by 50% to 75% in individuals who were ER-positive.

Additionally, when the HER2 status was taken into consideration, the differences in HRR between the two cohorts were most pronounced for the first 5 years for patients positive for HER2 and negative for ER, as well as for HER2-negative individuals regardless of ER status, write the authors in the Journal of Clinical Oncology.

Karen Gelmon and co-investigators also found that the contemporary cohort had a lower mortality risk than the historic cohort except for the first yearly interval.

They point out that “[t]he benefit from chemotherapy is known to occur mostly in the initial 3 years after treatment”, but add that “[t]he improvements seen in our study extend throughout the follow-up period, likely representing both improved treatment strategies and increased screening.”

The team concludes: “Contemporary patterns of disease recurrence according to [breast cancer] characteristics and subtypes are of [utmost] importance to adequately inform patients and physicians about prognosis and also to guide planning of future clinical trials.”

Reference

Cossetti RJ, Tyldesley SK, Speers CH, et al. Comparison of Breast Cancer Recurrence and Outcome Patterns Between Patients Treated From 1986 to 1992 and From 2004 to 2008. J Clin Oncol 2014; Advance online publication 24 November. doi:10.1200/JCO.2014.57.2461

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