Annette M. Boyle
WASHINGTON – Men are diagnosed with less than 0.1% of all breast cancers, but for those unfortunate few, the disease extracts a high toll — and a 65% increase in mortality risk compared to women.
The interpretation of the odds rates are not as straightforward as they might appear, however.
“We don’t have data on why patients died,” said Anita Aggarwal, DO, PhD, a hematologist/oncologist with the Washington, DC, VAMC. “They may have died of cancer or of something else. Men tend to be older when diagnosed and have more comorbidities that could contribute to the difference in mortality rates.”
Alternatively, the higher mortality rates in male breast cancer could result from “higher stages at diagnosis or be a consequence of tumor biology. That’s something we need to research further,” Aggarwal added.
At the Association of VA Hematology/Oncology (AVAHO) professionals conference in September and the 2014 American Society of Clinical Oncology (ASCO) meeting in August, Aggarwal and colleagues at the Washington VAMC presented their findings of gender disparities in breast cancer based on the analysis of 6,443 patient records in the VA Central Cancer Registry (VACCR). The 1,123 male patients and 5,320 female patients received treatment at 153 VAMCs between 1998 and 2013. About 75% of both male and female patients were white and 25% were black. 1
As of December 2013, 355 of the male breast cancer patients, 32%, had died compared to 791,15%, of the female breast cancer patients. The researchers found that males had 65% higher odds of death compared to females with breast cancer, even after adjusting for age, race, stage and grade of tumor.
“The first notable difference was that males were significantly older than females at time of diagnosis,” Aggarwal told U.S. Medicine. The mean age for diagnosis for men was 70 compared to 57 for women. Nearly all male breast cancer patients (95%) were over the age of 50. In women, 28% received a breast cancer diagnosis in their 40s or younger.
Male veterans also presented with more advanced cancer, with 40% having Stage III or IV cancers at the time of diagnosis, compared to less than one-fourth of women. “Men don’t have screening mammograms and don’t palpate their breasts monthly as many women do,” Aggarwal noted.
Men have only a 1 in 1,000 lifetime risk of breast cancer, so regular screening at home or in clinic is not recommended. In comparison, women have a lifetime risk of 1 in 8.
“In women with breast cancer, 21% are diagnosed during mammograms with ductal carcinoma in situ (DCIS).” Only 8% of men are seen with DCIS, Aggarwal said, partly because of the very rudimentary physiology of the male breast; 92% of men have invasive ductal carcinoma.
Male breast cancer patients typically first notice a mass under the nipple or nipple retraction that leads them to seek out care, she explained. In the study presented at AVAHO, she noted that 62% of males with breast cancer had tumors of two centimeters or greater on presentation.
Breast cancer in males also has different biological characteristics. Male breast cancers are much less likely to overexpress human epidermal growth factor receptor 2 (HER2), 5%, compared to more than 20% of female breast cancers. More than 90% of male breast cancers are estrogen- or progesterone-receptor (ER/PR) positive, while 60% to 70% of female breast cancers are ER or PR positive.
Despite these differences in tumor biology, treatment for breast cancer in males follows the same basic protocols as breast cancer in females, Aggarwal pointed out. In adjuvant treatment, aromatase inhibitors such as anastrozole and letrozol are used less often in male breast cancer than in female breast cancer, however. Because of the very high prevalence of HR-positive tumors, men typically receive tamoxifen.
Male breast cancer patients in the study were more likely to receive hormonal treatment as a first course of therapy (45% to 36%) but were somewhat less likely to receive chemotherapy and radiation.
Choosing appropriate treatment for female breast cancer can be informed by oncotype-testing that may indicate how likely the patient is to suffer a relapse. That testing is not commonly done for men.
“I don’t know why we don’t look at oncotype in male breast cancer, except that there are so few studies that could tell us whether the test has the same relevance in male breast cancer,” she noted.
Aggarwal and others involved in breast cancer research met at AVAHO for the first time to discuss creating a more formal breast cancer research group within the VA. Currently five or six institutes are involved, Aggarwal noted, but she aims to gain participation from all facilities — and encourages anyone interested in participating to contact her.
“Our goal is to create a data bank for all male and female breast cancers so that we can analyze the tumor biology, incidence and treatments prospectively,” she said. “We need to be able to better understand which men and women are at high risk for developing breast cancer or having a relapse. To do that we need to have tissue storage and key data for a much larger patient population.”
1Aggarwal A, O’Neill BR, Maron D, Amdur RL, Krasnow SH. Gender disparity in breast cancer: a veteran population-based comparison. J Clin Oncol 32:5s; 2014 (suppl; abstr 1606).
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