MedicalResearch.com Interview with:
Mitchell H. Gail, M.D., Ph.D.
Division of Cancer Epidemiology and Genetics
National Cancer Institute National Institutes of Health
Rockville MD 20850-9780
Medical Research: What is the background for this study?
Dr. Gail: In the United States, breast cancer survival following diagnosis has been improving since the 1970s. We wanted to understand what might explain these shifts, to fully characterize the changes over time, and to explore whether tumor size and estrogen receptor status could help explain the trends in age- and stage-specific breast cancer death rates after diagnosis.
We evaluated survival from breast cancer from the date of diagnosis of all women diagnosed with invasive breast cancer in the US SEER Cancer Registries between 1973 and 2010. We excluded women with ductal or lobular carcinoma in situ. We analyzed separate age groups (<50, 50-69, 70+ years) and SEER stage of disease (local, regional, distant).
Medical Research: What are the main findings?
Dr. Gail: Between 1973 and 2010, breast cancer death rates after diagnosis in the United States have fallen for each age group of women diagnosed with local or regional stage disease, not only in the first five years after diagnosis, but also thereafter. For women under age 70, rates also fell for women with distant disease.
Changes in tumor size or estrogen-receptor status do not explain much of the improvement among women under age 70 years, but do explain roughly half the improvement in 70+ year old women in the first five years after diagnosis.
Medical Research: What should clinicians and patients take away from your report?
Dr. Gail: There have been long-term favorable trends in breast cancer survival following diagnosis. Women under age 70, who received more intensive treatment than older women, seem to have benefited from such treatment, because their survival improvement was not explained by changes in tumor size or estrogen-receptor status and because even younger women with distant disease had improved survival. Some of the improvements in 70+ year old women may be related to treatment and some to detection of smaller lesions and improved care, indicated by a decreasing proportion with unknown estrogen-receptor status.
Our study had some limitations. SEER does not provide detailed treatment data on breast cancer patients; thus the argument in favor of treatment is indirect. Our study focused on survival improvements within disease stage. Possible benefits from screening mammography in shifting the stage distribution were not studied, but the stage distribution has been stable since about 1990. Other unidentified changes in the nature of the tumors diagnosed within stage may also have played a role.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Gail: Continued advances in treatment, especially for metastatic disease, are needed in order to bring death rates down further. Additional study is needed to explain a decreasing ratio of estrogen- receptor positive to estrogen-receptor negative tumors, and to understand the relationship of our stage- and age-specific findings to declining overall US breast cancer mortality rates.
Mitchell H. Gail, M.D., Ph.D. (2015). Long Term Survival After Breast Cancer Diagnosis Has Increased For All Age Groups