Biology of Disease

An exciting development in immunotherapy has been the production and

clinical trials of a number of anticancer vaccines based on tumor associated

antigens. Examples include vaccines based on peptides derived from

carcinoembryonic antigens, and the BiovaxID™ vaccine for the treatment

of follicular lymphoma, a type of nonHodgkin’s lymphoma involving B

lymphocytes.

17.8 Specific Types of Cancers

Cancer patients, naturally, may present with a variety of symptoms depending

on the origin and extent of the tumor. The treatment administered for any

cancer patient therefore depends to a large extent upon the type of cancer

present, its location, the stage of the disease and the age and health of the

patient. Major concerns in the developed world include lung, breast, prostate

and colorectal cancers and these are discussed below. The leukemias will also

be discussed as examples of tumors arising from bone marrow stem cells.

Lung Cancer

Almost 29 000 deaths were attributed to lung cancer (Figure 17.30) in England

and Wales in 2002 and around 37 000 new cases are diagnosed annually. In

the USA lung cancer is, again, the second most common malignancy after

prostate cancer in men and breast cancer in women, with over 160 000 new

cases occurring each year. Worldwide, about one million new cases occur

annually, with an incidence of 37.5 new cases per million population amongst

men, and 10.8 cases per million amongst women.

Trachea

Tumor

Left lung

Figure 17.30Schematic illustrating the presence of a cancer of the lung.

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Lung cancer is a fatal disease and, in England and Wales, only approximately

20% and 6.0% of patients survive one year and five years respectively after

diagnosis. These figures are higher in the USA, where the five-year survival

figure stands at about 14%. Overall, lung cancer is the most frequent cause of

death from cancer in men, who make up around 60% of all lung cancer cases.

In women, lung cancer is the second commonest cause of cancer death after

breast cancer. The risk of lung cancer increases with age with approximately

75% of deaths occurring after the age of 65.

A link between smoking and cancer is indisputable and smoking and passive

smoking are the cause of 90% of lung cancers. The carcinogens in cigarette

smoke include benzo[a]pyrene, a polycyclic hydrocarbon and N-nitrosamines,

both of which are metabolized by the cytochrome P-450 enzymes in the

liver to carcinogens that form adducts with DNA as described in Chapter

12. Radon, a naturally occurring radioactive gas produced from the decay of

uranium and which is found at relatively high indoor levels in homes built