Some men with breast cancer may be having unnecessary radiotherapy, according to new research published (Wednesday 22 June) in Annals of Oncology.
A study carried out at the British Columbia Cancer Agency in Vancouver, British Columbia, Canada, showed that men whose cancer had not spread beyond the breast were almost six times more likely to be given radiotherapy than were women with the equivalent stage of disease.
Many men receive radiotherapy routinely after a mastectomy because the smaller male breast makes it harder for surgeons to leave a clear margin of healthy tissue when they remove the tumour, so men are perceived to be more at risk of the tumour recurring in the breast area.
But an analysis of 60 male breast cancer patients and more than 4,000 female control patients, showed that gender was not a prognostic factor in recurrence, breast cancer survival or overall survival.
"What this means is that if we do have presumptions about prognosis purely on the basis of sex we would do better to ditch them and apply the same guidelines for radiotherapy treatment to men as we do for women," said lead author, Dr Graham Macdonald, a consultant in clinical oncology at Aberdeen Royal Infirmary, Scotland, who was a fellow in radiation oncology in Vancouver at the time the study was carried out.
He said that there was an ongoing debate whether post-mastectomy radiotherapy in men should be guided by the same principles used in women or given routinely to all men with breast cancer, but the new results were consistent with there being no influence of gender on the main outcomes once other known prognostic variables were taken into account.
However, he emphasised that because of the low numbers of male breast cancer patients available for analysis, the power of the study to detect possible small differences was low.
The study drew on men and women diagnosed in British Columbia between the start of 1989 and the end of 1998 who had undergone total mastectomy, excluding certain categories of patients. This left 60 men and 4,181 women where direct comparisons could be made with a median follow-up of 8.4 years (men) and 10 years (women).
"Statistically significant predictors for receiving radiotherapy after surgery included tumour size, the status of the margins around the tumour, whether chemotherapy was given and whether the nodes were affected," said Dr Macdonald.
"But when we added the sex of the patient into the analysis we found a statistically higher proportion of men (5.82 times) than women received adjuvant radiotherapy, even when these other predictive factors were accounted for. We also found men were more likely to have adjuvant hormonal therapy then women, but that was because there was a higher proportion of men who had oestrogen-positive tumours. An equal proportion of men and women (one-quarter) received chemotherapy."
The breast cancer survival rates were 89% and 81% at 5 and 10 years for men and 88% and 79% for women. There was no difference between male and female breast cancer survival whether or not radiotherapy had been given.
Overall survival was 75% and 53% for men at 5 and 10 years and 82% and 65% for women. There was no difference in survival between men and women who had received radiotherapy, but men who had received no radiotherapy had poorer overall survival than women receiving no radiotherapy.
The reasons for giving, or withholding radiotherapy appeared to be different for men and women – men being withheld radiotherapy when they had poorer outlook than women and women being withheld radiotherapy when they had a better outlook.
"Said Dr Macdonald "A key finding is that males who did not receive radiotherapy had poorer overall survival than females. Given that breast cancer-specific survival was equivalent between these two groups, this suggests that co-morbidity rather than good prognostic factors was a major reason for not giving radiotherapy in males.
"We could find no evidence that gender is a prognostic factor for loco-regional relapse-free, breast cancer specific or overall survival following mastectomy once known prognostic factors and delivery of adjuvant radiotherapy were accounted for. This suggests that males should receive adjuvant therapy following similar guidelines to females."