**3. Results**

Over the study period, there was an increase in the number men diagnosed with cancer. Approximately 20% of men with breast cancer were diagnosed in 2000–2004 compared to 28% in 2015–2019. The mean age at diagnosis was 66.1 (standard deviation: 11.7; median 66) years, with more than half of them (52%) living in the west region of the United States at the time of cancer diagnosis. The racial and ethnic distribution of the sample are as follows: non-Hispanic White, 75%; non-Hispanic Black, 12%; and Hispanic, 7%. Only 12% of men diagnosed with breast cancer lived in counties with median household incomes

of less than \$50,000. With regards to receipt of cancer treatment, 38.8% and 28.4% of men reported receiving chemotherapy and radiotherapy, respectively, with the median time from diagnosis to treatment being 1 month. Characteristics of participants according to the first course of cancer therapy received are reported in Table 1.

**Table 1.** Characteristics of men at the time of breast cancer diagnosis according to cancer therapy, SEER program (*n* = 5216).



**Table 1.** *Cont.*

ER: estrogen receptor, PR: progesterone receptor status.

Over the period of the study, the proportion of patients who received radiotherapy (with or without chemotherapy) increased while the proportion of patients who received chemotherapy reduced with age. Additionally, a greater proportion of patients who received both chemotherapy and radiotherapy had stage III cancer while the proportion of patients with mastectomy was lowest among those who received radiotherapy alone.

During a median follow-up of 5.6 years (interquartile range: 2.6 to 9.8), 1914 deaths occurred with 25% and 35% attributable to CVD and breast cancer, respectively. Characteristics of patients at the time of diagnosis according to cardiovascular disease mortality status are presented in Table 2. Of the 485 CVD deaths, 64.5% occurred among patients who received neither chemotherapy or radiation, 14.6% occurred among those who received chemotherapy but not radiation, 11.8% occurred among patients who received radiation but not chemotherapy, and 9.1% occurred among patients who received both chemotherapy and radiotherapy. Similarly, among the 1914 all-cause mortality cases, 55.7% occurred among patients who received neither chemotherapy nor radiation, 19.1% occurred among those who received chemotherapy but not radiation, 10.2% occurred among patients who received radiation but not chemotherapy, and 15.0% occurred among patients who received both chemotherapy and radiotherapy.

**Table 2.** Characteristics of men at the time of breast cancer diagnosis according to cardiovascular disease mortality status at the end of follow-up, SEER registry (*n* = 5216).


