New Delhi, Aug. 2: Mammography may benefit some women but harm an even greater number, according to sections of medical researchers concerned about campaigns urging women in their 40s or older to undergo periodic screening for breast cancer.

Two community medicine experts in the US said today there was significant evidence to indicate that while periodic mammography may reduce the risk of dying from breast cancer by a small amount, it also leads to over-diagnosis and unnecessary treatment and harms patients.

Lisa Schwartz and Steven Woloshin from Dartmouth Medical College said higher survival rates after early screening were being misinterpreted as evidence that screening saves lives. 'If there were an Oscar for misleading statistics, using survival statistics to judge the benefits of (mammography) screening would win a lifetime achievement award,' they said in a report to appear tomorrow in the British Medical Journal .

A breast cancer specialist at the Tata Memorial Centre, Mumbai, said the words of caution were relevant to India where oncologists and radiologists in the private sector have been urging women to undergo periodic screening through mammography. 'Mammography is an excellent diagnostic tool in the management of the disease but periodic screening, particularly for women in their 40s, is all about making money,' Rajendra Badwe, director, TMC , told The Telegraph . 'It has nothing to do with saving lives.'

Schwartz and Woloshin point out that while screening can help detect more early-stage cancers, the benefits of such screening cannot be determined by comparing survival rates for early and late-stage cancers. The statistics from screening show both benefit and harm.

Screening through physical examinations alone typically picks up only palpable breast tumours. However, screening with mammography allows doctors to detect tiny seeds of cancer that may never trouble women.

'For every one woman saved by mammography, two to 10 are likely to be harmed through unnecessary chemotherapy, radiation or surgery,' Woloshin told The Telegraph via email . 'Cancers behave differently. Some cancers are never destined to cause any symptoms or death. Since they are not destined to kill, women treated for them cannot experience benefit from therapy. They only experience harms and complications of therapy.'

Sections of imaging specialists and oncologists are questioning such assertions.

'Yes, some cancers do not advance to symptoms, but we have no tool today to predict which lesion will progress and which one will not,' said Chandra Shekhar Pant, former president of the Indian Radiology Association.

Ramesh Sarin, an oncologist at the Apollo Indraprastha Hospital, said there was still significant support for once-a-year mammography screening for women above 50, as tiny suspect lesions detected early can be scooped out without the need for full cancer therapy. 'But this is a controversial issue, and some oncologists don’t support routine screening,' she said.

Pant said the guidelines expected to be followed by radiologists and oncologists in India invite women to undergo a baseline mammography between 35 and 40, a screening once every two years between 40 and 50, and an annual screening above 50.

But TMC director Badwe says mass screening would only push up the numbers of women diagnosed with early breast cancer, many of whose cancers would never have troubled them. 'There is no evidence from anywhere in the world to support claims of mortality reduction from periodic mammography screening of women below 50 years,' Badwe said. 'This is important for us in India because 87 per cent of our population today is below 50.'

Badwe said one of the largest and longest studies in Canada that compared the death rates of breast cancer among women who had mammography and physical examination and physical examination alone found no difference in death rates. 'But there were 22 per cent excess cancers in the mammography group, after 17 years of follow-up. This tells us that while mammography can detect impalpable tumours in this age group, it does not save lives.'

A 10-year study of nearly 39,800 breast cancer patients in Norway found that the incidence of breast cancer increased by 18 per cent to 25 per cent among women invited to undergo breast cancer screening through mammography.

'Over-diagnosis and unnecessary treatment of non-fatal cancer creates a substantial ethical and clinical dilemma, and may cast doubt on whether mammography screening programmes should exist,' Mette Kalager, a surgeon at the Oslo University Hospital, who also holds a position at the Harvard School of Public Health, and her co-authors wrote earlier this year in the journal Annals of Internal Medicine .

Schwartz and Woloshin have said the problem of over-diagnosis has been demonstrated [ ] across the US and Europe where mass screening programmes have existed for many years . 'There is no reason to think that India would be different,' Schwartz said.

'We think women in their 40s should understand the benefits and harms — and make a decision with their doctors,' Schwartz said.

'We are fortunate here in India that we do not have a public screening programme through mammography, we're advising against it,' Badwe said. 'This is possibly one reason why the rate of increase of breast cancer in India is lower than that in Western countries that introduced mass screening.'

But many oncologists still believe the number of women who opt for screening needs to increase. 'Despite our advocacy, not enough women are sensitised to the need for screening,' said Sarin, who estimates that only about five per cent of urban women in India in their 40s or older get themselves screened through mammography