Surgery for breast cancer can promote secondary tumor

Reported by Susan Aldridge, PhD, medical journalist

A new study suggests that surgery for breast cancer may sometimes stimulate the growth of a second tumor.
Although mammography helps detect breast cancer early and so can save lives by hastening treatment, it has an odd effect in some women aged 40-49. Known as the 'mammography paradox', it is the observation that there is a temporary excess in mortality from breast cancer in those screened compared to those not screened. Now researchers at the Children's Hospital, Boston, USA, believe they have found another link in this puzzle.

They looked at data from 1,173 women who had had surgery for breast cancer, but no further treatment. They found two 'peaks' for relapse - one at 18 months and one at five years. Closer analysis revealed that 20 per cent of premenopausal node-positive cancer patients relapsed ten months after surgery. The researchers believe that surgery may stimulate the formation of a new blood supply - angiogenesis - that can feed dormant metastases. Why this happens is unclear. But primary tumors secrete angiogenesis inhibitors and once removed, angiogenesis may occur. In fact cancer recurrence following surgery has been known for 100 years. This is not to say that younger women with breast cancer should avoid surgery - but after-treatment should be designed with this kind of recurrence in mind. The study shows that we still do not understand everything about the biology of cancer.

Source
International Journal of Surgery online 12th September 2005