Recently, I came across a letter from a batch of Australian pathologists writing in to The Lancet (2002; 360: 1101). In the letter, I was stunned to read their assertion that, in performing core biopsies for abnormalities picked up on mammograms, they routinely uncover cases of ‘burnt-out’ - that is, healed - ductal carcinoma in situ. These are cases of a calcified mass which was DCIS and which seems to have run its course.

The Australians were very wary of saying that this finding cannot always be counted on to be benign and suggested continued follow-up.

Nevertheless, this letter also indicated something even more astonishing: that this phenomenon - of a DCIS healing - was first described in the medical literature some 70 years ago (J Pathol Bacteriol, 1934; 38: 117-27).

It’s important to understand something about DCIS. First of all, it’s the most common form of breast cancer there is and the variety that’s on the greatest increase. The American Cancer Society estimates that 41,000 new cases of DCIS are diagnosed every year, making up some 25 per cent of all diagnoses of breast cancer. The usual treatment is a lumpectomy or full mastectomy, followed by radiation. Although DCIS is treated like any other invasive cancer, it is classified as a stage 0 cancer - that is, a cancer that hasn’t spread anywhere.

DCIS is contained in the milk ducts of the breast and hasn’t spread out to the fatty breast tissue or any other part of the body, such as the lymph nodes. It is not large enough to be palpable, but is only picked up on mammograms, where it shows up as little specks of calcium (referred to in medicalese as ‘microcalcification’).

It is usually confirmed by either a fine-needle aspiration biopsy, which removes fluid and fragments of breast tissue, or a core-needle biopsy, which removes a larger chunk of breast tissue for examination under the microscope.

As the Australian boys say, repeatedly they have found that at the centre of these microcalcifications is a ‘foci’ of a cancer that has basically petered out. All that is left is a remnant of the old problem, which the body has effectively contained - an abnormal milk duct or a calcified mass surrounded by fibroid tissue.

The implications of these findings are enormous. For many years, doctors have admitted that they don’t know whether DCIS spreads, and they perform mastectomies precisely as a just-in-case measure. Now we have evidence that, in many instances, these could be little fires that the body is well equipped to stamp out by itself, without having to enlist the full support of the cut-and-burn fire brigade of modern medicine.

These findings also suggest that many cases of so-called breast cancer - up to one-fourth of the current cases - are being mislabelled as such.

Finally, they also highlight how blunt an instrument mammography is as a form of detection. By indiscriminately detecting all abnormalities, including benign ones, mammograms are contributing to the problem, and not the solution, of breast cancer. Most cases of DCIS might have resolved by themselves with no one the wiser if it had not been shown up by a mammogram.

There is no doubt that the incidence of breast cancer is rocketing upward. But the true number of cases of dangerous breast cancer may be vastly inflated by the blunderbuss tools of modern medicine.