About 2000 New Zealanders a year are diagnosed with breast cancer, including a handful of men.
Male breast cancer makes up just one per cent of all cases detected - so about 20 cases annually - but breast surgeon Dr Belinda Scott says it looks like men may be stronger carriers of the cancer gene.
"We think male breast cancer is probably going to have a genetic risk for it," Dr Scott, director of Breast Associates, told nzherald.co.nz.
"It's quite different in that only 10 per cent of our females with breast cancer will carry the gene. A lot more, we think, of the men will have the gene.
"We haven't tested enough of the men to know it and we don't get enough men around, we just know that it is more common for men to have a genetic type of cancer."
Dr Scott treats a couple of men each year for breast cancer, all aged over 50. She said all were surprised to find the lump in their chest or irregular nipple was actually the pink ribbon disease.
"They all go, 'Oh my God, what do you mean I've got breast cancer?'," she said.
Aucklander Andrew Kininmonth, was diagnosed with breast cancer in 2004.
Sore ribs prompted him to get a chest x-ray which revealed an abnormality around his left nipple.
Kininmonth, now 74, was so surprised to find out he had breast cancer he "said some rude words".
"They did a couple of mammograms and it came back... and I was told that the breast had to be removed or I could have chemo or radiotherapy. At that stage I was at my late 60s and I wasn't too fussed about losing a breast... so they took it out."
The following year he went for a check-up and discovered the same thing in the right breast.
"I said take it off, it will match the other one.
"She did tell me I was a bit unusual, because they don't get a lot of men."
Men usually undergo a full mastectomy, before assessing if further treatment like chemotherapy, radiotherapy or anti-oestrogen tablets are needed, Dr Scott said.
Most "do quite well".
For the last couple of years, all men have been sent for genetic counselling in a bid to prove Dr Scott's suspicion about the strong genetic link. She said details will become clearer over the next decade.
"The importance of that for them is their children," she said.
"So if dad's had breast cancer the children are at a much greater risk than if mum's had breast cancer.
"Mum with breast cancer over the age of 50 is probably just a mutation and one of those things and I wouldn't have said to her daughters, 'you've got a low increased risk'.
"Dad's got breast cancer, I think, 'Whoa, this could be a gene, you need to go and get yourself checked from the age of 40'.
"That's quite a different thought to what we first had."
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