Cancer diagnosis

Frank Muscat (The Sunday Times, July 8) has understandably had an unfortunate bad experience with his wife's cancer diagnosis and management, which possibly diminished her chances of cure and accelerated her demise, so his skepticism about aspects of current cancer management are justified.

One of the very relevant points he makes in his articles is the lack of a PET (positron emission tomography) scanner in Malta, even in the expensive Mater Dei Hospital. PET scanners have been in use overseas for cancer diagnosis and follow-up for several years; they are superior to other scanners in certain diagnostic situations.

However, they are not only very expensive to buy and maintain, but they also raise logistical problems because they require a constant supply of radioactive material that would have to be transported to Malta. I understand there are at least one or two PET scanners in Sicily, rendering recent claims that Mater Dei is one of the world's top hospitals a trifle bombastic.

Top quality modern medicine is all about how good and motivated the human resources are, how good the equipment is, and whether the most modern drugs are being used (rather than cheaper, less effective, obsolete ones). A new building undoubtedly improves morale of staff and patients, but should be of secondary importance when one is determining priorities for rationing limited financial resources from law-abiding taxpayers' pockets.

Mr Muscat goes on to knock mammographic screening for breast cancer, quoting from a certain Dr Ralph Moss, Ph.D., apparently not a medically qualified scientist. Nobody claims mammography is a perfect screening test, but the majority view around the world is that currently it is the best general purpose breast screening test (combined with ultrasound) we've got.

Whether a cancer screening test is any good is measured by how much it reduces mortality from that cancer, and mammography has been proven to do that not only by old Swedish and American trials, but more recently in the British NHS, which has one of the most organised national breast screening programmes in the world.

Mammography is less effective at picking up cancer in younger women than in the over 50s. For young women at high risk of breast cancer (due to family history, etc.), MRI (magnetic resonance imaging) appears to be safer (no X-rays) and more accurate, but costs around 10 times as much as mammography and requires radiologists experienced in its interpretation.

Quoting further from Dr Moss, Mr Muscat extols the merit of breast self-examination (BSE) and clinical breast-examination (CBE), but no one anywhere in the world has proven that these, on their own, actually reduce breast cancer mortality, and the reason is obvious. Breast cancers picked up by the patient herself, or the doctor's hand, are on average 2 cm-2.5 cm (about an inch) in diameter.

Swedish mammographic screening trials were the first to prove that picking up breast cancers when they are still 1 cm or less in diameter reduces mortality. There is no way you can feel such small cancers deep within a breast.

Furthermore, mammography picks up some pre-cancerous lesions and may therefore prevent some cancers developing. The claim that mammographic breast compression (or palpation of a breast lump by several medical students in teaching hospitals) encourages cancer spread is also unproven. Whether or not, and how fast or slow, cancer cells spread is determined by their "computer programme" inside their altered DNA, and not by breast compression or palpation.

Mr Muscat quite rightly highlights the crucial importance and pitfalls of pathological cancer diagnosis, because this is still essentially a subjective professional opinion based on one's experience. The most serious mistakes are those where young patients have been subjected to limb or breast amputations, or to extensive radiotherapy and chemotherapy, for what were in reality non-cancerous conditions.

Also very serious are patients dying from perfectly curable infective conditions mistaken for incurable cancer. I won't take up more of this column space with accounts of some astounding mistakes I've seen committed in centres of excellence in London, southern England and New York. The only people who never make mistakes are armchair critics.