The treatments for DCIS and invasive breast cancer can themselves lead to severe side effects, including death.
Breast cancer treatments do carry risks of morbidity and even mortality. Common morbidities reported with breast cancer treatment include cardiac complications, wound infections, lymphedema (swelling of lymph vessels as a result of fluid buildup), impaired range of shoulder motion, loss of libido, and psychological distress. Of these, the morbidity of greatest incidence is lymphedema.
Immediate morbidity from radiation therapy is typically reported in the form of dermal reactions, but long-term consequences can include new cancers. Consequences of chemotherapy can include cardiovascular damage, peripheral neuropathy, infertility, and other cancers, too. Morbidity from the hormonal therapy tamoxifen includes endometrial cancer, thromboembolic disease, and ocular toxicity. Tamoxifen also increases the risk of endometrial cancer and venous thromboembolism. These are just a handful of the side effects that can result from common breast cancer treatments.