William Aiken

A diagnosis of cancer generally conjures up images of pain, suffering and death but, where prostate canceris concerned, these outcomes are not necessarily inevitable even when no treatment is administered.

Prostate cancer is not a uniform or homogenous disease but has a wide spectrum of biologic aggressiveness. At the lower end of the spectrum are indolent or clinically insignificant cancers which do not appear to cause a problem and, therefore, should not be diagnosed or treated as treatment is entirely unnecessary. At the upper end of the spectrum are aggressive tumours which, if untreated, will invariably result in the death of the patient given a long enough period of observation. Overall, prostate cancer is much less aggressive than lung, colon or stomach cancer, and time to death from prostate cancer when diagnosed early is approximately 10 to 15 years, if no treatment is given.

The prevalence of prostate cancer increases with age such that by the age of 90 years, 100 per cent of men will harbour cancer cells in the prostate. The vast majority of these cancers is insignificant and, therefore, will not threaten life. Moreover, as early clinically significant cancers will cause death in 10 to 15 years, it is generally felt by most experts that screening for prostate cancer beyond 70 to 75 years of age is counterproductive as the average life expectancy is 72 years. That said, the merits of screening a particular individual 70 years and older would encompass assessing his physiologic age and parents' age of death to determine whether extended life expectancy is likely and screening therefore beneficial.

Non-curative treatment

What does a diagnosis of prostate cancer, therefore, mean to the individual patient faced with the dilemma of having to decide on what treatment option to proceed with? A number of factors need to be taken into consideration. Firstly, the age and life expectancy of the patient is paramount. Fit and healthy men in their 40s, 50s and early 60s will almost certainly die from prostate cancer if it is not treated when diagnosed and, therefore, curative treatmentwith a track record of durability of cure should be offered and accepted. Regardless of age, the presence of illnesses which curtail survival, such as severe heart, lung, liver or kidney disease should influence the decision to have either no treatment or non-curative treatment such as hormone therapy only, as cure in this setting is unnecessary. Indeed, persons with serious illnesses which curtail normal life expectancy should not be screened for prostate cancer at all.

Secondly, the characteristics of the cancer itself are important in deciding on which treatment is best. The stage (the extent of spread of the cancer), and grade (an assessment of the degree of aggressiveness of the tumour) are two key determinants of prognosis and treatment. Low-stage, early, tumours are still confined to the prostate and are curable by removal of the prostate or radiotherapy, whereas high-stage, late tumours have already spread either in a continuous (direct extension) or discontinuous (metastatic) manner and are no longer curable but are still imminently treatable with hormone therapy plus or minus radiotherapy.

High-grade cancer

The level of the prostate specific antigen (PSA), the assessment of the prostate on digital rectal examination (DRE), and the grade of the cancer as determined by a pathologist, determines the likely stage of the cancer. Magnetic resonance imaging, CT scanning and bone scans are helpful in selected circumstances in assessing stage. Low-grade cancers rarely threaten survival but are not commonly diagnosed. Most prostate cancers are of an intermediate or high grade and definitely warrant treatment. High-grade cancers are particularly sinister because they may exhibit no overt evidence of spread yet have already metastasised in a covert or undetectable manner only to declare themselves later on when treatment for seemingly localised disease has failed.

The impact of the various treatments on the cancer and on the patient overall, their common side-effects and how these impact on quality of life both at the time of treatment and over time are also important considerations in deciding on which treatment best suits a particular individual and will be considered in more detail in the next article.