CANCER CARE AND TREATMENT MODALITIES
The essential principle underlying the distribution of cancer care between modalities is that around 30% of cases are only very locally invasive – for example, basal skin cancers (commonly called rodent ulcers) – and require a very limited local therapy, usually surgery but occasionally radiotherapy. Of the rest, around 40% of patients end up with widespread cancer and 30% have locally advanced cancer, which can be eradicated by local/regional treatments such as surgery or radiotherapy. As already indicated the precise split varies in part by geography but also varies with anatomical site. For example, cancer of the colon is best treated with surgery rather than radiotherapy, as a normal large bowel is relatively intolerant of radiotherapy, and also targeting a mobile structure is clearly problematical. On the other hand, cancer of the uterine cervix (neck of the womb) is now predominantly treated by radiotherapy combined with simultaneous chemotherapy, with surgery reserved for salvage cases plus a limited role in assessing the disease for local spread.
Of the patients who end up with advanced cancer, around half present with this in the first place, the other half starts out with apparently localized disease but then subsequently relapse with more widespread problems. Of patients who develop advanced (usually called metastatic) cancer, the majority will have an essentially incurable disease. These will be diseases like advanced lung, bowel, breast, prostate, or liver cancer – the major cancer killers. A minority will have potentially chemocurable diseases such as testicular cancer, lymphoma, leukaemia, or certain childhood cancers.
It can be seen from this breakdown that the majority of patients cured of cancer in the 21st century are treated with modalities developed initially in the 19th century – surgery and radiotherapy. The major drug treatment advances, which drive so many of the news headlines, started in the mid-20th century and mostly extend lives in advanced disease rather than actually curing patients. This fact is well known to public health doctors but less well appreciated by the general public. It follows from this that in poorer economies; the maximum impact on cancer will be obtained by putting in place good basic surgery and radiotherapy. The best illustration of this is the survival rates worldwide for rectal cancer, for which the best results are obtained in Cuba, renowned for its well-organized medical care but with very limited access to the more expensive new drugs. Where resources are limited, cancer chemotherapy is best focused on the rare chemocurable cancers such as childhood leukaemia and testicular cancer. As these cancers mostly occur in younger people, the impact of drug spend in this area on life-years saved is disproportionately high compared to spending on end-of-life cancer drugs in older patients. Drug therapy for advanced disease occurring in later life tends to have a much smaller impact on cure rates. Even if cures were common, the patients themselves are older and thus have more limited life expectancy anyway.