Barone-Adesi F, Ferrante D, Bertolotti M, Todesco A, Mirabelli D, Terracini B, Magnani C.

Unit of Cancer Epidemiology, CeRMS and Center for Oncologic Prevention Piemonte, University of Turin, Turin, Italy.

Abstract

Models based on the multistage theory of carcinogenesis predict that the rate of mesothelioma increases monotonically as a function of time since first exposure (TSFE) to asbestos. Predictions of long-term mortality (TSFE >/= 40 years) are, however, still untested, because of the limited follow-up of most epidemiological studies. Some authors have suggested that the increase in mesothelioma rate with TSFE might be attenuated by clearance of asbestos from the lungs. We estimated mortality time trends from pleural and peritoneal cancer in a cohort of 3,443 asbestos-cement workers, followed for more than 50 years. The functional relation between mesothelioma rate and TSFE was evaluated with various regression models. The role of asbestos clearance was explored using the traditional mesothelioma multistage model, generalized to include a term representing elimination over time. We observed 139 deaths from pleural and 56 from peritoneal cancer during the period 1950-2003. The rate of pleural cancer increased during the first 40 years of TSFE and reached a plateau thereafter. In contrast, the rate of peritoneal cancer increased monotonically with TSFE. The model allowing for asbestos elimination fitted the data better than the traditional model for pleural (p = 0.02) but not for peritoneal cancer (p = 0.22). The risk for pleural cancer, rather than showing an indefinite increase, might reach a plateau when a sufficiently long time has elapsed since exposure. The different trends for pleural and peritoneal cancer might be related to clearance of the asbestos from the workers’ lungs.

Keywords: asbestos, mesothelioma, multi-stage model, latency, clearance

Glossary

mortality

a measure of the rate of death from a disease within a given population.

epidemiology

(ep-uh-deem-ee-AHL-uh-gee) the study of diseases in populations by collecting and analyzing statistical data. In the field of cancer, epidemiologists look at how many people have cancer; who gets specific types of cancer; and what factors (such as environment, job hazards, family patterns, and personal habits, such as smoking and diet) play a part in the development of cancer.

cancer

malignancy; a group of diseases typified by abnormal, generally out-of-control, cell growth.

mesothelioma

a tumor derived from mesothelial tissue, such as the peritoneum (lining the abdomen) or pleura (lining the lungs). More on mesothelioma.

peritoneal

(pair-uh-tuh-nee-al) the serous membrane that lines the cavity of the abdomen. (More on Peritoneal Mesothelioma.)

Bjelkengren G, Glimelius B.

Department of Oncology, University Hospital, Malmo, Sweden.

Abstract

A Swedish group of oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy. The estimations have been based on current statistics of tumour incidence, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours and normal tissues. It is estimated that about 350 patients with lung cancer and about 20 patients with mesothelioma annually may benefit from proton beam therapy.

Glossary

therapy

any of the measures taken to treat a disease. Unproven therapy is any therapy that has not been scientifically tested and approved. Use of an unproven therapy instead of standard (proven) therapy is called alternative therapy. Some alternative therapies have dangerous or even life-threatening side effects. For others, the main danger is that a patient may lose the opportunity to benefit from standard therapy. Complementary therapy, on the other hand, refers to therapies used in addition to standard therapy. Some complementary therapies may help relieve certain symptoms of cancer, relieve side effects of standard cancer therapy, or improve a patient's sense of well-being. The ACS recommends that patients considering use of any alternative or complementary therapy discuss this with their health care team.

oncology

(on-call-o-jee) the branch of medicine concerned with the diagnosis and treatment of cancer.

cancer

malignancy; a group of diseases typified by abnormal, generally out-of-control, cell growth.

mesothelioma

a tumor derived from mesothelial tissue, such as the peritoneum (lining the abdomen) or pleura (lining the lungs). More on mesothelioma.