Breast cancer survivors have a higher risk of developing new primary cancers than the general population. This is due, in part, to shared risk factors between breast cancer and some other cancers, as well as the long-term effects of breast cancer treatment. Now a new study has reported that mortality may also be higher among breast cancer survivors.

Second primary cancers

The cumulative rate of second primary cancers among breast cancer survivors has been estimated between 4% and 8%. Survivors have been observed to have higher risks of the following cancers than the general population:
  • Digestive tract cancers (bile duct, gallbladder, liver, thorax, stomach (especially among lobular BC survivors), lower & upper GI tract)
  • Endometrial cancer
  • Esophageal cancer
  • Kidney cancer
  • Leukemia
Significantly increased risks of second cancers have been linked to increasing BMI. Generally speaking, having been diagnosed with breast cancer at a young age (under 40) is linked to increased risk of a second cancer, as is being African American (especially for endometrial cancer). The implication is that breast cancer survivors must pay attention to possible cancer symptoms and get regular health care, including cancer screenings, as appropriate.

Latest research finds mortality is higher for BC survivors

The study referenced above was designed to investigate survival outcomes after second primary cancers ("second cancers") among women who have been treated for first primary breast cancer ("survivors"). Results of previous studies suggest that prognosis of some cancers may be less favorable for survivors than for others with first primary cancers of the same type.
To conduct the study, the authors analyzed records of 63,424 U.S. women using the Surveillance, Epidemiology, and End Results 18 database (2000–2016), comparing mortality after a second cancer among survivors to that of matched women with the same cancer type (i.e., as their first cancer). The analysis included adjustment for prognostic factors and included a median follow-up period of 42 months.
A total of 11,532 cancer-specific deaths took place after second cancers among survivors compared to 9,305 among women with first primary cancers. Cumulative cancer-specific mortality was found to be 44.7% for survivors compared to 35.2% for women with first primary cancers. Survivors had a 27% higher risk of cancer-specific death and an 18% higher rate of death from all causes.
Increased rates of cancer-specific mortality after second cancers in survivors (compared to women with first primary cancers) was found for cancers of the breast, lung, colon and/or rectum, uterus, and thyroid, as well as for lymphoma, melanoma, and leukemia. The mortality difference was influenced by estrogen receptor status, treatment of the original breast cancer, and time between initial breast cancer and second cancer. The authors comment that a more focused approach to early detection and treatment could improve outcomes of second cancers in survivors.