Risk of Development of Second Primary Head and Neck Cancer following an Index Breast Cancer.

Objective Many head and neck cancers (HNCs) have genomic features seen in breast malignancy. We sought to analyze the risk of second primary HNC following an index breast cancer. Study Design Retrospective cohort study. Setting National database from the SEER registry (Surveillance, Epidemiology, and End Results). Subjects and Methods Within the SEER database, 223,423 women diagnosed with index breast cancer from 1992 to 2002 were identified. We calculated standard incidence ratios (SIRs) for all head and neck sites with 10-year follow-up. Results Women diagnosed with an index breast cancer did not exhibit higher likelihood of developing second primary HNC (SIR = 0.99; 95% CI, 0.90-1.07). The risk was determined for each subsite of the head and neck, and salivary gland cancer presented the highest risk. Patients with index breast cancer were 83% more likely to develop salivary gland cancer than what would be expected in the general population (SIR = 1.83; 95% CI, 1.49-2.22). An overall trend of increased risk was observed for salivary gland cancers between 1992 and 2002. There was no significant higher risk observed for the other head and neck subsites. Conclusion Patients with index breast cancer did not have a higher-than-expected risk of developing HNC. We did find an increased incidence of salivary gland cancers among patients with index breast cancer. Patients were 80% more likely to develop salivary gland cancer than that expected within the population. These findings warrant further investigation on the relationship between salivary gland and breast malignancy.