The National Cancer Registry (NCR) reports cancers diagnosed by the historically, haematology and cytology laboratories in South Africa. The South African Institute of Medical Research (SAIMR) and now called the National health Laboratory Service (NHLS) established the national cancer registry in 1986. It is a cooperative venture of the Department of Health, the Cancer Association of South Africa, the National Laboratory Service and the University of Witwatersrand. The NCR is a voluntary cancer notification system and it receives copies of pathology reports from both public and private laboratories nationally. In a year, about 80 000 cancer cases are reported and of these approximately 55 000 are new cases. Cancer incidence is reported in annual incidence reports, which are available from the national Cancer Registry.
The cancer registry methodology and procedures follow those of the World Health Organisation -International Agency for Research (WHO-IARC). The laboratories report cancer cases in various disease classification formats. At the registry, these are standardized following the IARC International Classification of Diseases on Oncology (ICD -O second edition) and are reported in the ICD-10 format. Incidence rates are expressed per 100 000 population and excludes basal cell carcinoma (BCC) and squamous cell carcinoma of the skin (SCC of skin). On average, BCCs comprise about 18% and SCCs of skin 5% of the total cancers reported in a year. These occur most frequently; particularly among white population and tend to overshadow all other cancers in this population group.
This article reports the cancers diagnosed in 1997 and were published in October 2003. A total of 29 208 new cancer cases in females and 29 499 new cancer cases in males were reported in 1997. One in fort males ad one in five females (adjusted to under-reporting), aged 0 to 74 years, were at risk of developing cancer. The five most common cancers in males are prostate, lung, oesophagus, bladder and colorectal while in females are cervix, breast, colorectal, oesophagus and lung.
Risk factors for developing cervical cancer include primarily certain types of the Human papilomavirus (HPV), early initiation of sexual intercourse, a history of sexually multiple sexual partners (or a partner with multiple sexual partners), a history of sexual transmitted infections. Lower socio-economic status has been associated with a higher risk of developing cervical cancer, probably due to lack of access to good health care and Papanicolaou (Pap-smear) test. Although only a small proportion of women infected with HPV development cervical cancer, recent studies have shown that women with high parity or who have used hormonal contraceptives long-term (more than five years) are more likely to develop cancer of the cervix than those who have used contraceptives less or with lower parity.
Well-implemented and successful cervical screening programmes have been reported to reduce the incidence of cervical cancer significantly. The South African cervical cancer-screening policy and the programme implemented since 2001 are attempts to reduce the incidence of cervical cancer, which is the leading cancer among South African women. Three smears per lifetime are recommended for the program, commencing after the age of 30 and with a 10-year interval between each smear. The ultimate goal is to reduce cervical cancer incidence rates by 60%.
A total of 5 318 new cases of the cervix cancer were reported in 1997. Cervical cancer cases comprised 18.2% of all cancers reported in 1997. The risk of developing the cancer of the cervix among South African women (aged 0-74 yrs) was 1 in 29 women.
Cancer of the cervix had consistently been the leading cancer in females. I was the leading cancer amongst blacks females who constituted about 85% of all cervical cancer cases. Black females had highest AS of 38.5 per 100 000. The lifetime risk of developing cervical cancer in black females was twice that of Asian females and 2,4 times that of colored and white females combined.
The cancer of the cervix in coloured and white women combined, constituted the second highest proportion (14%) to that in black women, with the lowest ASR of 15.91 per 100 000. Asians had the least number of female cancer cases and had the second highest ASR of 19 per 100 000.
Cervical cancer rates in Africa, especially in black females, are among the highest in the world. The incidence rates observed in South Africa black women in 1997 are similar to those reported in Kyadondo, Uganda, whilst those in South African-Asian females compare with those in Bombay, India.
Risk factors for female breast cancer include early menarche, late age at first childbirth, a high-fat diet and certain genetic mutations, including BRCA1/2. Other suggested risk factors include, to a lesser extend, high alcohol consumption, contraceptives use and the use of certain post-menopausal hormone replacement therapies. At present, there are no breast cancer screening or prevention programs in South Africa.
A total of 4 789 new cases of the female breast cancer were reported and these comprised 16.4% of all cancers reported in females in 1997. The risk of developing the cancer of the breast among South African women (aged 0-74 yrs) was 1 in 31 females.
Asian breast cancer cases comprises 6.8% of all female breast cancer cases. Despite the low proportion of cases, Asian females had the highest breast cancer incidence rates compared to other population groups and this was the leading cancer among Asian females. The AS was 66 per 100 00 in 1997, about a 60% increase on that reported in 1995. The lifetime risk of developing breast cancer in Asian females was 1 in 3 females.
Coloured and white females combined comprised the largest proportion (55%) of all female breast cancer cases. As with the Asian females, breast cancer ranked the leading cancer in coloured and white females in 1997. The ASR ranged from 51.9 per 100 000 in 1996 to 55.5 per 100 000 in 1997. Black females comprise 38.4% of all breast cancers in 1997 and had the second highest number of breast cases to coloured and white females. Breast cancer comprised 14.6% of all black female cancers and was the second common cancer in the black females. They had the lowest incidence rate of 15.8 per 100 000 and their lifetime risk of developing breast cancer was 1 in 57, four times lower than that reported in Asian coloured and white females.
The breast cancer incidence rates among South African-Asian females are the highest as compared with those reported in the USA, England and Wales. The risk of developing breast cancer in South Africa-Asian females are 2.6 times higher than that reported in Bombay. The risk for South African-Black females compare well with those reported in other countries.
Cancer of the lung is the most frequent cancer worldwide, with a wide geographical variation in risk. The main course of lung cancer is tobacco smoking, for which there is a clear positive linear relationship between the magnitude of cancer and the smoking period and/or the amount smoked (dose-response relationship). Other known causes of lung cancer include domestic and industrial pollution. There is evidence that both of these contribute to lung cancer incidence in South Africa.
A total of 813 new cases of the cancer of the lung in females and 1 974 new cases in males were reported in 1997. These comprised 2.8% of all females cancers and 6.7% of all male cancers. The lifetime risk of developing lung cancer among South Africans (aged 0-74 yrs) was 1 in 49 in men and in women, the risk was three times lower at 1 in 153.
Colored and white males combined had the highest lung cancer incidence rates. These also constituted the second largest proportion of lung cancer cases, comprising 38.8% of all male lung cancer cases. Lung cancer was the third leading cancer in males in 1997, comprising 4% of colored and white male cancers. The AS in colored and white males was 20.3 per 10000 and the lifetime risk was 1 in 38. Lung cancer was the fifth leading cancer in the colored and white females, constituting on average 3% of all colored and white female cancers. Colored and white females constituted the bulk of lung cancer cases in females, and comprised 58% of all female cancers. Lung cancer AS in colored and white females was 10.6 per 100 000 with a lifetime risk of developing lung cancer being 1 in 79.
Asian males and females comprised 4% of all lung cases in males and in females; and 10.6% of all Asian male cancer per year. In 1977, it was the second leading cancer in males with an AS of 19.9 per 100 000. The lifetime risk of developing lung cancer in Asian men was similar to that in colored and white males being 1 in 38. Asian females constituted 3% of all lung cancers in females. Lung cancer ranked the seventh leading cancer in Asian females in 1997 and comprised 2.7% of all Asian female cancers. The AS was 6.6 per 100 000 in 1997 and the lifetime risk of developing lung cancer was 1 in 127.
Although having the lowest lung cancer incidence rates of all population groups, black males constituted the largest proportion (57%) of all lung cancer cases in males and were 11.2% of all cancers in black males with and AS of 13.6 per 100 000 in 1997. The lifetime risk was 1 in 59. Black females comprised 38.2% of all lung cancers in females. Lung cancer ranked the fifth common cancer and comprised 2.5% of all black female cancers. The AS was low at 3 per 100 000 and the lifetime risk was 1 in 286.
The highest lung cancer incidence rates occur in developing countries. South African-Asian have higher rates than Indians in Bombay, with the risk of developing lung cancer in South African females twice of the female in Bombay.
Prostate cancer is one of the leading cancers in men worldwide. Incidence rates vary from 1 to 100 000, suggesting that environmental factors play a role in its aetiology. Risk factors for prostate cancer include diets high in fat and low in vegetables. There is a suspicion that infections may play a role, but the agent(s) responsible has not been isolated. In many western countries, the incidence of prostrate cancer is increasing, possibly due to the increasing use of prostrate specific antigen (PSA) as a screening tool.
A total of 3 715 new cases of the cancer of prostate were reported in 1997. These comprised 12.6% of all male cancers. The lifetime risk of developing prostrate cancer among South African males aged 0-74 years was 1 in 24.
Prostate cancer was the leading cancer in all population groups and incidence rates showed an increase on the number reported in 1995. Coloured and white males comprised 63.4% of all prostate cancer cases and had the highest ASR of 63.5 per 100 000. In 1997, one in 12 coloured or white South African men were at risk of developing prostate cancer.
Asian men comprised 2.5% of all prostate cancer cases, with a shift from colorectal cancer as the leading cancer in 1995 to prostate cancer in 1997. Asian males had the second highest incidence rates to those of coloured and white males. In 1997, incidence rates increased almost two-fold, from 18.9 per 100 00 in 1996 to 32.4 per 100 000 in 1997. The lifetime risk of developing prostate cancer among Asian men was 1 in 29 in 1997 almost two times that in black males and 2.4 fold lower than that in coloured and white males.
Black males constituted the second-hihest proportion of cancer cases and comprised on average 34% of all prostate cancer cases. A shift from oesophageal cancer as the leading cancer in black males in 1995 to prostate cancer in 1997 was observed. The lifetime risk of developing prostate cancer was 1 in 47.
A general increase in prostate cancer rate had been reported worldwide (IARC 1998). Incidence rates among South African coloured and white males combined ranks among the highest in the world and are second to those reported in the USA. These rates compare with those reported in white males in Zimbabwe. Rates in South African-Asian males are almost five times those reported in Bombay, India. Rates in South African-Black males compare with those reported in other developing countries.
HIV is thought to facilitate the existence of the other cancers causing infectious agents due to its effect on the immune system, thereby promoting the development of cancer. Other cancers that had been declared as HIV and AIDS defining include the cancer of the cervix, non-Hodgkin lymphoma and conjuctival cancer. Among the AIDS defining cancers, since 1992, Kaposis sarcoma is the only cancer that has shown significant increase in South Africa. Although the observed KS incidence rates were still low in 1997, KS had increased three fold in South African men and five fold in South African women with significant increases observed particularly among Black males and females (four and six fold increase respectively). In Uganda and Zimbabwe, KS increase more that 20 fold following the HIV epidemic, and although it used to occur rarely, KS became one of the leading cancers in these countries.
Compiled by Nokuzola Mqoqi(Cancer Registry)
Reviewed by Matsie Ratsaka-Mothokoa
For more information, contributions or ideas on this issue of Research Update contact:
The National Department of Health
Directorate: Health Systems Research, Research Co-ordination and Epidemiology
Private Bag X 828
Pretoria
0001
Tel: (012) 312 0960
Fax: (012) 312 0784
Copies of the reports are available from the Cancer Registry.
Research Updates are quarterly publications of the Department of Health, focusing on the important/current research findings.