Survival has increased substantially for young women with breast cancer since 1975, though it has largely reached a plateau since around 2005.
Survival increased substantially for young women with breast cancer since 1975, though it has largely reached a plateau since around 2005, according to a new analysis. Young women with metastatic disease continue to see improvements up through the present day.
“Advances in systemic therapy for breast cancer have greatly improved patient survival rates,” wrote study authors led by Fangjian Guo, MD, PhD, of the University of Texas Medical Branch at Galveston. “However, quantifying the effectiveness of these advances on cancer survival rates at the population level is challenging, because mammography screening also contributes to survival improvement.”
The researchers examined data from the Surveillance, Epidemiology, and End Results (SEER) database; they included women age 20 to 39 years diagnosed with breast cancer between 1975 and 2015. The results were published in Cancer.
In 1975, the age-adjusted incidence of breast cancer was 24.6 per 100,000 individuals; this rose to 31.7 per 100,000 by 2015. The age-adjusted incidence of ductal carcinoma in situ rose from 1.1 per 100,000 in 1975 to 3.5 per 100,000 in 2015, and the incidence of metastatic disease rose from 1.3 per 100,000 to 3.0 per 100,000.
Follow-up data were available for 39,129 women in the database. The 5-year survival rate rose from 72.7% in the period between 1975 and 1979 up to 87.4% in the most recent period, from 2010 to 2015. The corresponding breast cancer–specific survival increased as well, from 74.0% to 88.5%.
The increases in survival and cancer-specific survival appear to have reached a plateau in 2005. For overall survival, the 5-year rate was 86.3% in the 2000–2004 period, 88.3% in the 2005–2009 period, and 87.4% in the 2010–2015 period. There was an exception to this trend in those with metastatic disease: the 5-year overall survival rate in those patients rose from 33.9% in the 2000–2004 period to 43.6% and then 54.2% in the subsequent two study periods. This was also true for cancer-specific survival among those with metastatic disease.
The authors cite the improvements in systemic therapies-tamoxifen and other hormone therapies, targeted therapies, and HER2-directed agents such as trastuzumab, among others-as a primary reason for the improvements in survival over time. Other factors could include changes to risk factors such as smoking, oral contraceptive use, parity, and others.
“This is a fascinating and at the same time terrifying [study],” said Balazs Bodai, MD, director of the Breast Cancer Survivorship Institute at Kaiser Permanente in Sacramento, California. “Indeed, advances in survival have stalled in the last decade … [and] we continue to fail to address the root cause of breast cancer development. Why are younger women getting breast cancer in the first place?”
Bodai, who was not involved with the research, said it will now be important to focus on prevention, in part to improve some of those risk factors and others like earlier onset of menarche. “My hope is that … we take advantage of the opportunity to implement early and effective messaging of lifestyle changes.”