Cancer

Mesothelioma and Asbestos

Mesotheloima is a rare neoplasm (cancerous neoplasm) that arises from mesothelial cells lining the parietal and visceral pleura of the lungs. Mesothelium is the protective lining that covers most of the internal organs (including lungs) of the body.

The commonest site of mesothelioma is the pleura, which is the outermost lining of the lungs and the chest wall. But mesothelioma can occur at any site where mesothelial cells lining is present like peritoneum, heart etc.

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The Global Magnitude of the Problem of Cancer

Cancer afflict all the communities throughout the world. At present more than 11 million people are diagnosed with cancer and more than 7 million people die due to cancer every year, throughout the world. More than 30 million people are living with cancer at present. In term of incidence, the most common cancers are Lung cancer (12.3% of all cancer), breast cancer (10.4%) and colorectal cancer (9.4%). In terms of death from cancer the most common cancers is Lung cancer (17.8% of all deaths due to cancer).

For a disease, the relationship of incidence to mortality rate is an indication of prognosis. Similar incidence and mortality rate is indication of essentially fatal condition. That is why lung cancer accounts for most deaths from cancer (1.1 million) in the world annually, because its incidence and mortality rate is similar and it is invariably associated with poor prognosis. On the other hand for breast cancer appropriate management can be effective in avoiding fatal out come. That is why although it is second in term of incidence but in terms of mortality it is ranked 5^th .

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Cancer control (Secondary prevention)

Secondary prevention comprises the following measures:

(1) Cancer registration:

Cancer registration is a sine qua non for any cancer control programme. It provides a base for planning the necessary services and for assessment of the magnitude of the problem of cancer. Cancer registries are of two types: hospital-based and population based registries.

(a) Hospital-based registries: The hospital-based registry includes all patients treated by a particular institution, both inpatients and out patients. Registries collect data as recommended by WHO in the “WHO Handbook for Standardized Cancer Registers”. If follow-up is long-term, hospital-based registries can be of considerable value in the evaluation of diagnostic and treatment programmes and also for research. Since hospital population will always be a selected population, the use of hospital-based registries for epidemiological purposes is limited.

(b) Population-based registries: The best thing to do is to set up a “hospital-based cancer registry” and extend it to a “population-based cancer registry”. 2-7 million is the optimum size of base population for population based registry. The aim is to cover the complete cancer situation in a given geographic area. The data from such registries alone can provide the incidence rate of cancer and serve as a useful tool for initiating epidemiological enquiries into causes of cancer, surveillance of time trends and planning and evaluation of operational activities in all main areas of cancer control.

(2) Early detection of cases:

Cancer screening is the main weapon for early detection of cancer at a pre-invasive (in situ) or pre malignant (cancerous) stage. Effective screening programmes have been developed for cervical cancer (Papanicolaou smear, known as pap smear), breast cancer (mammography) and oral cancer. Like primary prevention, early diagnosis has to be conducted on a large scale. But it is possible to increase the efficiency of screening programmes by focusing on high-risk groups. but there is no point in detecting cancer at an early stage unless facilities for treatment and after care are available. Early detection programmes will require mobilization of all available resources and development of a cancer infrastructure starting at the level of primary health care, ending with complex cancer centers or institutions at state or national levels (tertiary health care).

(3) Treatment:

Treatment facilities should be available to all cancer patients. Some of the cancers are amenable to surgical removal, while some others respond favorably to radiation or chemotherapy or combination of both. Since most of the known methods of treatment have only complementary effect on the ultimate outcome of the patient, multi-modality approach to cancer control has become a standard practice in cancer centers. In the developed countries cancer treatment is geared to high technology. For those who are beyond the curable stage, the goal must be to provide pain relief. A largely neglected problem in cancer care is the management of pain. The WHO has developed guidelines on relief of cancer pain “Freedom from cancer pain” is now considered a right for cancer patients.

Cancer control (Primary Prevention)

Cancer control consists of a series of measures based on present medical knowledge in the fields of prevention, early detection through screening and population education, diagnosis, treatment, after care and rehabilitation, aimed at reducing the number of new cases, increasing the number of “cures” and reducing the invalidism due to cancer.

The basic approach to the control of cancer is through primary prevention and secondary prevention. It is estimated that at least one third of all cancers are preventable. If we analyze the causes of cancer it is seen that environmental factors are the most important in causation of cancer which are modifiable. Genetic factors which are not modifiable are responsible in small number of cases of cancer.

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Causes of cancer

Cancer is a chronic disease. As with any other chronic diseases, cancer has a multifactorial etiology (cause). Carcinogens are the substances which can cause cancer to humans.

1. Environmental factors: Environmental factors are responsible for at least 90 per cent of all human cancers. The major environmental factors identified include the following:

a. Tobacco: Tobacco in various forms of usage (e.g. smoking, chewing, sniffing) is the major environmental cause of cancers of lungs, larynx, mouth, pharynx, esophagus, bladder, pancreas and also kidney. It has been estimated that cigarette smoking is responsible for more than one million premature deaths every year throughout the world in the form of cancer, respiratory problems and also in many other way. There is hardly any organ system which is not affected adversely due to cigarette smoking.

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Cancer: a General understanding

Cancer can be regarded as a group of most serious diseases which are characterized by (1) abnormal growth of cells without control. (2) ability to invade nearby tissues and even to distant organs, by local invasion, through lymphatic system and blood. (3) the eventual death of patient it the tumor (cancer) has progressed beyond the stage when it can be successfully removed by surgery . Cancer can occur at any site of the body and it can involve any type of cells.

If cancer occurs in a tissue, the cells of the tissue starts growing abnormally fast. But the cells can not mature and because cells are not mature they cannot perform the function for which they are present in the body. For example if there is cancer of liver (hepatocellular carcinoma) the cancerous liver cells cannot perform functions of liver, but they consume the nutrition and due to large number and fast growing they consume large number of calories. This is the reason of weight loss in cancer. These immature cells keeps growing in number without any function and may spread to nearby tissues or to a distant site through blood. One cancerous cell is enough for spread to distant organ which keep growing very fast.

Cancer can be categorized into the following major categories:

1. Caremomas :They arise from epithelial cells which is the cell lining the surface of various organs like mouth, uterus, intestines, stomach, inner side of nose etc, This type may arise from skin also from skin epithelium .
2. Sarcomas :They arise from various cells which constitute connective tissues like bone, fat, fibrous tissues, bran tissue etc.
3. Lymphomas, myelomas and leukemias (blood cancer) arise from the cells of immune system as well as from bone marrow. Blood cancer or leukemia arise from bone marrow, because blood cells are formed in bone marrow.

In blood cancer (leukemia) white blood cells, whose main function is to fight with the invading microorganisms (bacteria, virus, fungus etc), starts growing abnormally rapidly in bone marrow but they are not mature. Because of immaturity they can not perform their primary function, which is to fight with invading microorganisms. And patient eventually die due to infection.

The term primary (cancer) tumor means cancer in the organ of origin, but secondary (cancer) tumor means the cancer which has spread to distant organ or to regional lymph nodes. When cancer cells multiply and reach a critical size cancer can be clinically evident as mass or ulcer in the particular area. Some time primary tumor can not be detected or found, but the secondary tumor became the main cancer. In this type of cases the primary tumor shrinks due some reason and become undetectable.