Women diagnosed with early-stage breast cancer are more likely to become long-term survivors of the disease now than they were 20 years ago, a new study found.
Researchers at the University of Oxford (England) conducted an observational study that examined case fatality rates for women with breast cancer and found that the prognosis for women has “improved substantially” over the past few decades. For women diagnosed with early invasive breast cancer during the 1990s, the risk of death within 5 years of diagnosis was just over 14% on average. For women diagnosed during the 2010s, it was nearly 5% on average.
“The take-home message in our study is that it’s good news for women who are diagnosed with early breast cancer today because most of them can expect to become long-term cancer survivors, and so I think our results are reassuring,” said lead study author Carolyn Taylor, DPhil, a clinical oncologist from the Nuffield Department Of Population Health, University of Oxford.
The study was published online in the BMJ.
Although breast cancer survival has improved, recent estimates don’t incorporate detailed data on age, tumor size, tumor grade, and nodal and receptor status. In the current population-based study, researchers explored improvement in survival from early-stage breast cancer. They used nine patient and tumor characteristics as factors in their analysis.
The study is based on data from the National Cancer Registration for 512,447 women in England who were diagnosed with early-stage invasive breast cancer between 1993 and 2015. Women were broken into four groups: those diagnosed during 1993-1999, 2000-2004, 2005-2009, and 2010-2015.
The study focused on women who initially underwent either breast-conserving surgery or mastectomy as their first treatment. Data included age, tumor size, tumor grade, number of positive nodes, and estrogen receptor (ER) status. For women who were diagnosed from 2010 to 2015, HER2 status was included. Data regarding recurrence, receipt of neoadjuvant therapy, and patients who were diagnosed with more than one cancer were not included.
The major finding: Among women diagnosed with early-stage invasive breast cancer, the risk of dying decreased almost threefold between 1993 and 2015. The 5-year cumulative case fatality risk was 14.4% for women diagnosed in the 1990s (1993-1999) versus 4.9% for women diagnosed about 2 decades later (2010-2015).
Dr. Taylor and colleagues found that the case fatality rate was highest during the 5 years after diagnosis; within those years, the rates typically increased during the first 2 years, peaked during the third, and declined thereafter.
The 5-year risk of death, however, varied widely among women in the population. For most (62.8%) who were diagnosed between 2010 and 2015, the case fatality risk was 3% or less; however, for a small subset of women (4.6%), the risk reached 20% or higher.
Patients with ER-negative tumors tended to have worse prognoses in the first decade following their diagnosis. Overall, higher tumor size and grade, more positive nodes, and older age tended to be associated with worse prognoses.
Overall, the annual case fatality rates decreased over time in nearly every patient group.
While Dr. Taylor said these findings are encouraging, she added that the investigators did not analyze why survival rates have improved over 2 decades.
“We didn’t explain how much of the improvement was due to advances treatments, improved screening rates, etc,” Dr. Taylor said. Another limitation is that data on recurrence were not available.
Kathy Miller, MD, who specializes in breast cancer at the Melvin and Bren Simon Cancer Center at Indiana University, Indianapolis, said the 5-year mark for survival is great news for some patients with breast cancer but that the time frame doesn’t apply to all.
While the risk of case fatality from breast cancer may be higher during the first 5 years after diagnosis, Dr. Miller said that is not the case for women with ER-positive breast cancer. In the study, the researchers highlighted this trend for ER status: before the 10-year mark, survival rates for women with ER-positive disease were better, but after the 10-year mark, those with ER-negative tumors seemed to fare slightly better.
“Many patients have heard this very arbitrary 5-year mark, and for patients with ER-positive disease, that 5-year mark has no meaning, because their risk in any given year is very low and it stays at that very low consistent level for at least 15 years, probably longer,” Dr. Miller said in an interview. “I think a better way to think about this for ER-positive patients is that every day that goes by without a problem makes it a tiny bit less likely that you will ever have a problem.”
The authors took a similar view for the overall population, concluding that, “although deaths from breast cancer will continue to occur beyond this [5-year mark], the risk during each subsequent 5-year period is likely to be lower than during the first 5 years.”
The research was funded by Cancer Research UK, the National Institute for Health Research Oxford Biomedical Research Centre, the U.K. Medical Research Council, and the University of Oxford. Some study authors received support for several of these institutions, but they reported no financial relationships with organizations that might have had an interest in the submitted work during the previous 3 years.
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