New Study Finds Low Risk of Second Cancers After Early Breast Cancer Treatment

Recent research published in The BMJ provides reassuring evidence regarding the long-term health outcomes of women treated for early breast cancer. The study analyzed data from nearly half a million women in England diagnosed between 1993 and 2016, tracking the incidence of second primary cancers over a follow-up period of up to two decades. It found that the overall increase in the risk of developing a second cancer was modest, approximately 2–3% above the risk levels of the general population.

Specifically, about 13.6% of women developed a non-breast second cancer—most commonly affecting the womb, lungs, or bowel—representing a 2.1% excess compared to expectations. Additionally, 5.6% experienced a contralateral breast cancer, which is a new cancer on the opposite breast, with a 3.1% higher risk than in women without prior breast cancer.

The study revealed that age at initial diagnosis influenced the risk levels: younger women faced a higher relative risk of contralateral breast cancer, whereas the risk of non-breast second cancers was relatively consistent across age groups. Treatment type also played a role; radiotherapy was associated with increased rates of lung and contralateral breast cancers, while endocrine therapy was linked to uterine cancers, and chemotherapy correlated with a risk of acute leukemia. The researchers estimate that approximately 7% of the excess second cancers could be attributed to adjuvant therapies, but emphasize that these treatments' benefits in reducing recurrence generally outweigh the small risks.

While acknowledging some limitations due to incomplete data on family history, genetic predispositions, and lifestyle factors, the study offers valuable insights. It suggests that most women with early invasive breast cancer can be reassured about their relatively low long-term risk of developing additional cancers. The findings underline the importance of personalized treatment planning and provide useful information for clinicians and patients making informed decisions about breast cancer management.

Ultimately, these results highlight that the benefits of contemporary breast cancer treatments significantly surpass the minimal risk of secondary cancers, and that patients should have access to detailed risk information to better plan their futures.