History & Biography Holy Qur'an Islam in General Islamic Curriculums Islamic Law. Abdallah Al-Khabbas, Yusuf Shaheen, Ebrahim Abd Aljawad and Zeinat. Aimen Ansari, Nabil Sadoun, Ed.D and Majida Yousef, Aimma Shestar Clark. Arabic traditional folk-lore nasheed, Abu Ratib, Imad Rami and Sami Yusuf.

Several infectious agents are considered to be causes of cancer in humans. The fraction of the different types of cancer, and of all cancers worldwide and in different regions, has been estimated using several methods; primarily by reviewing the evidence for the strength of the association (relative risk) and the prevalence of infection in different world areas.

The estimated total of infection‐attributable cancer in the year 2002 is 1.9 million cases, or 17.8% of the global cancer burden. The principal agents are the bacterium Helicobacter pylori (5.5% of all cancer), the human papilloma viruses (5.2%), the hepatitis B and C viruses (4.9%), Epstein‐Barr virus (1%), human immunodeficiency virus (HIV) together with the human herpes virus 8 (0.9%). Relatively less important causes of cancer are the schistosomes (0.1%), human T‐cell lymphotropic virus type I (0.03%) and the liver flukes (0.02%). There would be 26.3% fewer cancers in developing countries (1.5 million cases per year) and 7.7% in developed countries (390,000 cases) if these infectious diseases were prevented. The attributable fraction at the specific sites varies from 100% of cervix cancers attributable to the papilloma viruses to a tiny proportion (0.4%) of liver cancers (worldwide) caused by liver flukes.

© 2006 Wiley‐Liss, Inc. In the last 30 years or so, considerable evidence has been found for a role for several infectious agents, particularly viruses, in human cancer.

In this article, I summarise the evidence for ‘causality’ with respect to infectious agents linked with cancer, and for each one that meets the established criteria, estimate the fraction of the cancer concerned that is attributable to it. These estimates update that for 1990, using new information on infection and cancer and the estimated global cancer burden in 2002. Those infectious agents that have been identified as causes of cancer (Groups 1 and 2A) in the IARC monographs series are included. They include hepatitis B and C viruses, human papilloma viruses (HPVs), human immunodeficiency virus (HIV), T‐lymphotropic viruses, Epstein‐Barr virus (EBV), human herpes virus 8, the bacterium Helicobacter pylori (HP), schistosomes and liver flukes (Table ). Cancer cases The estimated numbers of new cancer cases in the year 2002 by country, age group and sex are available for 25 of the major cancers in GLOBOCAN 2002. These estimates do not include certain cancers for which infectious agents apparently play a causative role: Burkitt lymphoma (in the case of EBV) and oro‐pharyngeal and ano‐genital cancers (vulva, vagina, penis and anus) in the case of HPV.

The incidence of Kaposi sarcoma (KS) is provided only for Africa, and appears only within the overall totals for other world areas. Separate estimates have, therefore, been made for these cancer sites. The estimates for oro‐pharynx cancer have been derived from the numbers of cancers of the pharynx (from Globocan 2002) and, for each world area, the proportion of such cases that are located in the oro‐pharynx, according to registry data in Cancer Incidence in Five Continents, volume VIII.

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Worldwide, the percentage of pharyngeal cancers localised to the oropharynx was about 45%. The total cases of oral cavity cancers includes a small percentage of cancers of salivary gland, presumably unrelated to HPV, but the correction involved to the estimates would be very small (certainly within the margin of error). For ICD‐10 categories C51‐52 (vulva and vagina) and C60 (penis), numbers of cases were estimated from cancer registry data (extracted from Cancer Incidence in Five continents, Volume VIII ) as the ratio of cases of cancer at these sites to cases of cervix cancer (C53) by age and area. The estimated numbers for 2002 are 40,000 annual cases of cancer of the external genitalia in females, and 26,300 cases of penile cancer worldwide.

Anal cancers were estimated from recorded ratios of colo‐rectal cancer to anal cancer (by age group, sex and area); the estimate is of 30,400 cases, about equally divided between males and females. Burkitt lymphoma is predominantly a disease of children and young adults, with few cases occurring after the age of 45. Based on the cancer registry database, the proportion of non‐Hodgkin lymphomas reported as Burkitt lymphoma at ages 0–14 and 15–44 in different areas of the world was estimated, and the corresponding number of cases were calculated (8,200 per year). Estimating the number of KS cases outside the African continent is rather difficult; the most recent systematic data on cancer incidence relate to cases occurring about 1995. With the advent of highly active antiretroviral therapy (HAART), however, the occurrence of clinical AIDS and its manifestations, including KS, has been much decreased. The age–sex specific incidence of KS reported by the cancer registries of the US SEER programme in 2000–2001 (excluding San Francisco, with its atypically high rates) have, therefore, been used to estimate the number of KS cases occurring in the United States in the year 2002.