CLINICAL CONDITIONS

EXERCISE AFTER CANCER DIAGNOSIS

By Prof Kerry Courneya

Cancer epidemiology It is estimated that nearly a quarter of a million people in the UK will be diagnosed with some form of invasive cancer in 2000 (1). More than 80% of these diagnoses will be in people aged 55 and older. The lifetime probability of developing cancer in the UK is about 40% (1) making it a highly prevalent disease. Fortunately early detection and improved treatments for cancer have resulted in increased sur- vival rates over the last few decades. The current estimated five year relative sur- vival rate is 31% for men and 43% for women for all cancers combined (1). This reality has placed an increased emphasis on understanding the quality of life (QOL) issues of concern to cancer patients and survivors.

Medical treatments Cancer treatments may be used to cure cancer, to prolong life when a cure is not possible, or to improve quality of life (ie. symptom relief). The three primary cancer treatment modalities are surgery, radia- tion therapy, and systemic therapy.

DEFINING CANCER

Cancer is not a single disease but rather a collection of many differ- ent diseases. What cancer cells have in common, however, is changes in the genes that regu- late cell division, programmed cell death, and cell mobility.

These genetic changes lead to the characteristic features of cancer which are:

(a) accumulation of abnormal cells

(b) invasion of nearby tissues (c) spread to distant sites

Cancers are classified into several groups depending on the kind of normal cell from which they arise. The most common cancers develop from epithelial cells that line the body’s surfaces and are called car- cinomas (eg. prostate, breast, colon, lung). Cancers can also arise from the cells of the blood (ie. leukemias), the immune system (ie. lymphomas), and bone and connective tissues (ie. sarcomas).

● Surgery is the oldest and most fre- quently used modality in cancer therapy and is the treatment of choice for most localised carcinomas and sarcomas ● Radiation therapy is the treatment of cancer using ionizing radiation. It is con- sidered a local-regional treatment with the goal to irradiate the known tumour volume while sparing adjacent radiation sensitive tissues ● Systemic therapy or chemotherapy (ie. drug treatment) is often used when can- cer cells have spread or metastasized beyond the primary site and regional lymph nodes. Cancer chemotherapy exploits biological differences between normal and malignant cells to preferen- tially kill malignant cells. Most of the cur- rently used chemotherapy drugs have been selected to be toxic to proliferating cells which, unfortunately, includes nor- mal cells and results in multiple side effects (Table 1).

Increasingly, combinations of the main cancer treatment modalities (ie. surgery, radiotherapy, and systemic therapy) are being used to treat cancer. Combined modality therapy is now the standard of care for high-risk or locally advanced solid

SportEX 17