Chicago has skyscrapers that rival the Tower of Babel more closely than anywhere else on earth: the Sears building is the tallest building in the Western world. The resemblance to the problems encountered after the collapse of the Tower of Babel were also obvious in Chicago this week, when more than 30,000 cancer experts gathered from across the world at the annual ASCO (American Society of Clinical Oncology) Conference to exchange ideas on the latest developments in oncology.

For the second or third year running, breast cancer was the hottest topic. The first major potential advance in treating the disease was not a new drug but a better and more efficient method of screening. After a long and initially fierce campaign to have mammography accepted, there is evidence that regular mammography should be replaced by MRI scanning.

For the time being, the campaign to reduce the three-year interval between breast screenings in Britain will continue. Efforts will also be made to encourage more women over 65 to have regular screening. There will also be pressure for more attention to be given by the NHS to detecting early breast cancer in younger women in high-risk groups. However, the evidence presented at ASCO in Chicago showed that, before long, those interested in the early diagnosis of breast cancer will be switching to MRI rather than mammography. Already the American Cancer Society is recommending MRI screening for high-risk individuals.

Having enough equipment to screen everyone who needs it was a problem when mammography was first introduced: there were also too few radiologists and radiographers who could interpret the mammography results or take good films. Similar difficulties are faced by those units that are introducing MRI scanning for the detection of preinvasive cancer.

Preinvasive breast cancer is of two types. The low-grade and slowly invasive variety is comparatively readily picked up by mammography, but the high grade is to all intents and purposes impossible to pick up by mammography at the early stage. Eventually, once the machinery and trained staff are available, switching from mammography to MRI scanning will become the breast-screening method of choice. It will increase the pickup rate for early tumours by 10 to 20 per cent.

So far as treatment is concerned, a mass of encouraging news about Herceptin was presented to the conference. A large survey has shown that the addition of Herceptin to chemotherapy before breast surgery significantly increases the response to it. It may even sometimes lead to the disappearance of the tumour, as well as in other cases a substantial shrinkage of the growth. Herceptin is effective in only 20 to 30 per cent of women with breast cancer, but in most of these cases the tumours are fast-growing and there is a high likelihood of relapse.

As well as providing survival benefits in advanced cases of HER2-positive breast cancer, giving Herceptin early now seems to be the best chance of achieving a cure in early HER2-positive breast cancer. It also lessens the extent of the surgery needed for some patients in whom the disease is locally advanced.

The statistics presented showed that when patients were treated early with Herceptin, as well as with other therapy, there was a 37 per cent reduction in the risk of death and a 51 per cent reduction in the risk of a cancer coming back within the first four years. In 86 per cent of women with HER2-positive breast cancer, previously more likely to be fast-growing and sinister, 86 per cent of women with HER2-positive tumours were tumour-free at the four-year follow-up examination.

Professor Ian Smith, of the Royal Marsden Hospital, London, said that these latest survival results showed the benefits of using Herceptin in addition to chemotherapy for early HER2-positive breast cancer. The survival figures recently released in Chicago represent many thousands of cases where lives have been prolonged, and also show a notably improved chance of a cure for this aggressive form of breast cancer.

There were hints of two encouraging pieces of research. There was chat about a new class of anticancer drugs known as HER dimerisation inhibitors (HDIs). One of these, R1273 (also known as Pertuzumab) is said to be showing signs of being able to block the union of HER2 and HER3. If this can be achieved, the response to treatment of HER2-positive tumours may leap ahead; one doctor who had been involved in the trials said that he hadn’t been so excited by results since he had first seen the effect of Herceptin.

Another development is the research into two new drugs. AZD2281 is designed to treat the markedly hereditary breast and ovarian cancers that are related to the gene BRCA1 and 2. These cancers are linked to an overactive DNA repair mechanism. AZD2281 is known as a PARP inhibitor: it stops the overenthusiastic natural repair of the broken DNA, an overexuberance that eventually leads to a malignant growth.

The other drug is the SRC kinase inhibitor. This also inhibits the growth of a damaged pathway that could lead to cancer formation.