Men with breast cancer are at a huge disadvantage because they are treated in the same way as women, experts have warned.

Breast cancer is usually thought of as a woman’s disease – but nearly 400 men receive a diagnosis in the UK each year.

Doctors have until now assumed the diseases are the same, whether they affect men or women - but the first major investigation into male breast cancer has revealed significant differences.

The discovery means that until now men may not have been treated in the best way.

Experts analysed 1,500 male breast cancer patients from nine countries – and found key differences were between their tumours and those of women

Experts analysed 1,500 male breast cancer patients from nine countries – and found key differences were between their tumours and those of women.

The project, led by the Erasmus Medical Centre in Rotterdam, revealed that male breast cancers have different connective tissue, contain different cells, and are affected by the immune system in a different way.

Speaking at the European Breast Cancer Conference in Amsterdam today, pathologist Dr Carolien van Deurzen, said: ‘Besides conventional tumour tissue characteristics, such as subtype and grade, we also examined additional features, such as the development of fibrotic connective tissue, and the density of tumour infiltrating lymphocytes, a type of white blood cell often found in tumours and implicated in killing tumour cells.

‘Interestingly, we found these two last factors were strongly associated with outcomes in male breast cancer, whereas tumour grade, a commonly used prognostic measure in female breast cancer was not.’

Grading compares breast cancer cells to normal breast tissue. It can tell doctors how aggressive tumours are in breast cancer patients.

But the study found a ‘lack of association’ between grading and the odds of men beating the disease - unlike in women.

Dr van Deurzen said the results could lead to ‘better treatment choices’ for male breast cancer patients in future.

Male patients are usually diagnosed later when their cancers are more advanced, which means they are more likely to die from the disease.

There is also poor awareness among men, and among GPs, about the risk of breast cancer.

Male breast cancers have different connective tissue, contain different cells, and are affected by the immune system in a different way than female breast cancer (above) researchers found

Scientists plan to use the discovery as part of clinical trials into how treatments can be better geared towards male patients.

Dr van Deurzen said: ‘This will only be possible with a worldwide collaboration, but it is also important that male breast cancer patients should take part in general breast cancer trials, since trials for them alone are difficult to run due to the rarity of the disease.

‘In the past, male patients have been persistently excluded, with no scientific rationale for doing so. In the meantime, we believe that our findings will help focus research in the field.’

Baroness Delyth Morgan, chief executive at Breast Cancer Now, said: ‘This study delivers much-needed insight into the biological differences between male and female breast cancer and could change how decisions about the necessity of chemotherapy for certain male patients are made.

‘Unfortunately the findings highlight the possible futility of using a current treatment planning tool for men, showing that grade – a marker of how different the cancer cells are from normal cells – was not linked to overall outcomes in male breast cancer in the same way that it is for women.