Health Matters – Cancer and Chemotherapy: A Primer

Cancer is a disease characterized by uncontrolled cell growth and proliferation. In healthy adults, cells grow and divide slowly but under tight control. This is to ensure that the number of cells in each tissue stays the same. Cancer may be viewed as one cell changing and rapidly growing out of control.

This rapid proliferation of cells from one cell to a growing mass of cancer cells is often called a tumour. Under normal conditions, the growth and division of normal cells is tightly controlled by the activity of certain genes. However, when these genes are faulty or when the mechanisms controlling the activity of these genes is damaged, this balance is compromised.

Moreover, this results in uncontrollable growth and division of cells; in other words, these mutated cells become cancerous. Cancer is caused by mutations in two broad classes of genes: oncogenes and tumour suppressor genes.

These two classes of genes are very important in controlling the cell cycle. The genes themselves do not cause cancer; in contrast, when the genes function normally, genes prevent cancer. It is when some genes become damaged that they can malfunction and cause cancer.

In some tumours, the tumour cells stay in the same place and the tumour stops growing before it becomes very large, often because it simply runs out of space to grow. These are called benign tumours. Under normal conditions, benign tumours are not dangerous. We all have benign tumours, such as moles and warts.

Conversely, some cells are able to invade the surrounding tissue and spread into nearby organs, where they can cause serious and eventually fatal damage. These are called malignant tumours. In many malignant tumours, as the cells spread, they cross blood vessels and may metastasize.

For instance, if they spread into the blood vessel, they get carried around the body and may eventually get lodged in a smaller blood vessel in another part of the body. As a result, the tumour divides and grows again eventually forming a new tumour, called secondary tumours.

Angiogenesis is another characteristic of cancer. Angiogenesis is the establishment of new blood vessels to provide vasculature for the tumour. This provides the tumour with more oxygen and nutrients so that it is able to support its rapid growth. Several therapeutic approaches are targeting the cessation of cell growth by cutting off the nutritional supply to tumour cells. Conventional methods include chemotherapy and this currently plays a significant role in cancer treatment.

Chemotherapy has played a major role in cancer treatment for over 50 years. The cure for cancer is elusive, but chemotherapy has the capacity to slow the progression of cancer, hence prolonging survival and enhancing the quality of life.

Chemotherapy is the treatment for cancer with cytotoxic (or cell killing) drugs. Chemotherapy may be given with a curative intent, or it may aim to prolong life or to reduce symptoms. Ultimately, chemotherapeutic modalities work by impeding cell division of rapidly proliferating cancer cells.

One of the main advantages of chemotherapy is that, unlike radiation therapy, which treats only the area of the body exposed to the radiation, chemotherapy treats the entire body. As a result, any cells that have escaped from the original cancer are treated.

Chemotherapy is useful in treating leukemia and lymphoma that are not confined to one part of the body. Other forms of cancer that can be treated fairly effectively with chemotherapy include colorectal, lung, and breast cancer.

In addition, chemotherapeutic drugs are very effective in slowing down the spread of cancer. Chemotherapy is also inexpensive and provides affordable treatment for cancer patients in need of long-term chemotherapeutic medications. Cancer cells become resistant to multiple chemotherapeutic drugs over time, and drug resistance is a significant challenge to researchers in developing successful treatment chemotherapy approaches to treating cancer.

For more information on cancer and treatments, visit the Canadian Cancer Society’s website.