On Cancer

All families are touched by cancer. It is estimated that one in three will contract cancer during their lifetime. There is a perception that the incidence of cancer is rising and that it is a relatively modern disease. But appearances can be deceptive. In times past the condition was under-diagnosed. Furthermore, we are living much longer than our ancestors. The average life span for an Englishman in the 18th century was 40 whilst today it is nudging 80. If cancer is anything, it is a disease of the aged; consequently we are seeing more cases simply because more of us are getting really old.

Until 1900 the only effective treatment for cancer was surgery. If the tumour was contained and not invasive, a cure was possible. More likely the tumour had infiltrated surrounding tissue or spread through the circulation and lymphatic system to other regions of the body. These 'seeds' would then lodge and start to grow. Under these circumstances, the patient was doomed. Radiation therapy for treating tumours came about in 1900. Some tumours are equisitively (definitely, not a real word) sensitive to radiation while others are tenaciously resistant. Normal tissue is also damaged, although there are techniques available to minimise collateral tissue damage.

Chemotherapeutic agents became available in the 1940s. This technique has evolved and proved very effective in the treatment of some cancers. However, it is still a relatively crude approach. The drugs are rather indiscriminate and target fast growing cells, regardless of whether they are malignant or healthy. Therefore, this technique is particularly effective against aggressive, fast growing tumours. Usually it has little potency against the indolent, slow growing variety. Chemotherapeutic drugs will also act on normal healthy tissue, especially if they are relatively fast growing. This is why cancer patients lose their hair and suffer from nausea as the drugs kill rapidly growing hair follicle cells and the cells lining the stomach. Often it is battle between killing the tumour before the chemical regime kills the patient. That said, there have been some notable success stories using chemotherapy. Childhood Acute Lymphocytic Leukaemia (ALL) was invariably fatal before chemotherapy. These days, 90% of children become long term disease free survivors.

In the 1960s, the Americans came up with a bold plan. What if they threw billions of dollars at the problem of curing cancer? Certainly the injection of money was welcome to the scientific and medical professions and the subsequent research certainly helped. However, after spending billions and billions of dollars on research a quarter of us are still dying of the disease. The pace of discovery didn't meet the politician’s expectations. Politicians truly believe that throwing money at a problem, solves all; consider the manned Moon mission programme. All falls prone to the mighty dollar. I am not trying to belittle the research work which followed. Much fundamental research occurred and great strides were accomplished. But the politicians and the suitably primed public expected a quick fix and cure. Unfortunately biology decided not to oblige. Those scientists and medics at the leading edge of research surmised that this problem was not going to be quickly resolved, but they kept their counsel, to themselves.

Cancer is not a single disease. Cancer is a multitude of diseases although they have the common denominator of being a genetic disease. Whenever a cell divides there is a preceding event of DNA replication. The fidelity of the process is astounding and an error occurs only once in ten billion base pairs. Even so, all is not lost as the organism has a surveillance system which picks up the errors and initiates a repair process. If the damage is too great, cellular destruct mechanisms come into play and the aberrant cell is eliminated. Why should this matter? It matters because genetic mutation within our cells drives the cancer process. It is an accumulation of genetic mutation which cause a cell to become cancerous. However, the efficient immune system is ever vigilant and detects mutant cells and destroys them. Therefore, cancer occurs when the repair process and the immune system becomes inefficient. As we age all our biological functions decline. Thus as we age we are more prone to cancer. Childhood cancer defies this explanation. There are other mechanisms at work here, but in my brief and simple survey, this will not be considered.

We live in exciting times and new targeted therapies are being introduced. As alluded to earlier, the problem with radiotherapy and chemotherapy is their inability to discriminate between normal and malignant tissue. Drugs have been developed which target the genetic defect. Aberrant mutant genes drive cancer growth. If we can turn off these genes then perhaps we can stop tumour growth and even cause tumour regression. There have been a few success stories. Chronic Myeloid Leukaemia (CML) is a cancer which, in the past, could only be cured by a bone marrow transplant. Only a minority of CML patients were eligible. Most patients were just too old to tolerate the procedure. And then there was always the problem of finding a compatible donor. Hence for most patients, the course of the disease was very predictable. The symptoms could be controlled for about three years, thereafter, the patients invariably developed an aggressive form of leukaemia which was intractable to treatment. And thus life was relinquished. The new drug (Gleevac) stops the gene from producing the protein which causes the blood cells to proliferate. This is not necessarily a cure. Some patients after a year or so develop further mutations which circumvent the treatment. However, second and even third generation drugs are now available to progress life.

Some cancers are close to being conquered although there remains a large group of malignancies which still defy medical science. But with continuing research and the relentless introduction of novel and effective drugs, there is hope that one day, perhaps not soon, most, if not all cancers, will be mastered.