Risk of Second Non-Breast Primary Cancer in Male and Female Breast Cancer Patients: A Population-Based Cohort Study
Hung MH, Liu CJ, Teng CJ, Hu YW, Yeh CM, Chen SC, Chien SH, Hung YP, Shen CC, Chen TJ, Tzeng CH, Liu CY
PLoS One. 2016 Feb 19;11(2):e0148597. doi: 10.1371/journal.pone.0148597. eCollection 2016
It has been a longstanding observation that people with cancer have a higher risk of developing a second, independent cancer, aside from the risk of the primary cancer recurring.
Many cancers have a shared genetic and/or shared environmental component. For example, tobacco use increases risk of lung, head and neck and also bladder cancer. HPV infection is associated with cervical and head and neck cancers. BRCA mutations are involved in breast and ovarian cancer.
Knowing what the added risk is, and specifically which second primary cancers are associated with a given primary cancer can inform patient surveillance. Since breast cancer patients are now living longer, thanks to advances in treatment, second primaries are becoming more common.
Here Hung and colleagues have studied a large number of patients in Taiwan with breast cancer, including men.
Focusing on the results for men with breast cancer, the main finding is that Taiwanese men have an increased risk of a second primary that is higher than for women at more or less all ages. Shown below in Fig. 1, you can see the standardized incidence ratio, which measures the relative incidence compared to a control population pegged at 1, is higher for men than women. In both genders it is higher for younger patients.
The second finding is what kinds of additional cancers men with breast cancer are susceptible to. Fig. 2 summarizes these data and shows that for men the most common secondaries are thyroid, skin and head and neck.
The standardized incidence ratio for these cancers was found to be
head and neck: 4.41
for men with breast cancer. Those are significant additional risks.
The first thing to note, is that a previous report of SEER data by Wernberg and colleagues from 2009 while also finding an increased risk, found one of much smaller magnitude – round 1.1, which is similar to the risk seen here for men 75 and older. Wernberg and colleagues did reach the same conclusion though:
Although MBC is uncommon, these patients are at risk of a contralateral breast cancer and second primary non-breast cancers. Our findings support that men with breast cancer would benefit from continued long-term surveillance for breast cancer and appropriate screening for non-breast cancers.
Similarly, Hung et al state:
From our analysis, we concluded that the risk of SPM was significantly higher for both male and female breast cancer patients compared with the general population, suggesting that more intensive surveillance may be needed, especially in high-risk patients.
Differences between the two datasets may related to age, as well as genetic and environmental differences between breast cancer patients in the USA and Taiwan. The ey commonality is that there is an increased risk. With these new data, some additional ideas for surveillance are provided.
On a personal note I do an annual skin screen with a dermatologist, and am being monitored for a thyroid nodule, the growth of which is being controlled by hormone therapy. My dentist also looks for oral cancers when I go for checkup twice a year. I hope to have the main bases covered.