There's also growing concern among doctors that some surgical techniques may themselves hasten the advance of the disease. It's now realised that tumours can remain quietly subclinical that is, not yet showing any symptoms but can begin to grow after surgery as a result of the immunodepressive effects of the operation (Ann Chir, 1998; 52: 413-20). There's also evidence that tumour cells may be released into the body during surgery, causing later metastases tumours which develop from cancer cells that spread through the body (Ann Surg Oncol, 1998; 5: 390-8). In particular, the new technique of laparoscopy has been called into question (Dis Colon Rectum, 1998; 41: 971-8). During laparoscopy, the endoscope is inserted into a small incision made in the wall of the abdomen, which runs a risk of cancer cell "spillage", potentially spreading the cancer.

Small wonder that a team of British oncologists traditionally less bullish than their American counterparts recently observed: "Despite advancement in surgical and anaesthetic techniques, there has been little reduction in mortality and morbidity from [colorectal cancer] over the past 25 years" (Eur J Surg Oncol, 1998; 24: 477-86).

The major problem with colorectal cancer is that, with or without surgery, the disease often spreads into other areas of the body, particularly the liver, lung and brain, where surgeons have a poor track record. So preventing metastases by chemotherapy has been the primary goal of oncologists.

Shortly after chemotherapy was invented 50 years ago, the toxic chemical fluorinated pyrimidine was developed into a drug called 5-fluorouracil (5-FU for short). Although 5-FU was increasingly used from 1953 onwards, for the first 35 years doctors were disappointed to find that although it might reduce tumour size, it had marginal effects on patient survival. Latterly, however, 5-FU has been combined with other cytotoxic drugs, and these cocktails are now widely prescribed for advanced cases of the disease following surgery.

Extraordinary claims are being made about them, with some doctors claiming a reduction in mortality as high as 33 per cent. But the surgeons are less flattering; some of their own studies show little benefit from the new chemical cocktails and even increases in mortality after their use (Am Surg, 1996; 62: 546-50).

A group of Canadian doctors recently reviewed the entire issue of chemotherapy from an angle relatively new to medicine: the value of therapy in terms of the patient's quality of life.

Quoting a review of a number of studies which showed that chemotherapy increases five year survival from colorectal cancer by an average of 7 per cent, they boldly stated: "Despite the US National Institutes of Health consensus statement endorsing chemotherapy, many clinicians regard such a seemingly small benefit not worth the expense, inconvenience, discomfort and risk of treatment for their individual patient with colorectal carcinoma" (Ann Chir, 1998; 52: 711-5).

Adding to the uncertainty of chemotherapy are its side effects. These are, of course, substantial since the treatment destroys healthy cells as well as cancerous ones. A recent study has shown a litany of side effects for patients whose immune systems are already compromised by the cancer. These range from nausea, vomiting and diarrhoea to thrombocytopenia (too few platelets), leukopenia (decrease in number of leukocytes) and neutropenia (decrease in number of neutrophils) (J Clin Oncol, 1998; 16: 3537-41).