CANCER EPIDEMIOLOGY, BIOMARKERS & PREVENTION | RESEARCH ARTICLE Changes in the Incidence of Cancer in Bulawayo, Zimbabwe over a 50-Year Period Donald Maxwell Parkin 1,2,3 , Tatenda Chingonzoh 4 , Samkeliso Vuma 4 , Biying Liu 2 , Eric Chokunonga 5 , Ntokozo Ndlovu 5,6 , and Margaret Borok 5 ABSTRACT ◥ Background: The cancer registry of Bulawayo (Zimbabwe) operated for 15 years in the preindependence period (1963–77), and was restarted in 2011. This allows comparison of incidence of cancers over a period of almost 50 years. Methods: Age-standardized rates, with SEs, were calculated for 1963–1972 and 2011–2015. Detailed results are presented for those cancers for which there was a significant (P < 0.05) change in the rates between the two periods. Results: There were declines in the rates of those cancers previously known to be common in East and Southern Africa (esophagus, liver, bladder), and the emergence of cancers asso- ciated with “westernization” of lifestyles (breast, prostate, large bowel). Cancers related to infection with HIV–AIDS (Kaposi sarcoma, non-Hodgkin lymphoma, eye cancers) have come to comprise a much larger proportion of the total burden, and cancer of the cervix (also AIDS-related) has shown a large increase in incidence—as elsewhere in sub-Saharan Africa (SSA). More surprising is the decline in cancer of the lung—formerly very high, but by 2011–2015, despite little change in the prev- alence of smoking, rates were low—close to the average for SSA. This may relate, in part, to a decline in the numbers of miners, and ex-miners, residing in the city. Conclusions: The changes in incidence are largely explained by differences in past exposure to environmental risk factors. Impact: Few datasets from SSA can document temporal changes in the cancer epidemic on the continent. There are some anticipated observations, as well as unexpected findings meriting further investigation. Introduction Bulawayo is the second largest city of Zimbabwe, with an estimated population (2020) of 776,953 (1). A population-based registry covering the municipality was founded in 1963 and functioned for 15 years. It was located in an office in the Radiotherapy Centre at the Mpilo Central Hospital (Bulawayo, Zimbabwe) which, in addition to pro- viding the only hospital service to the Black African population of the city of Bulawayo, also acted as the referral centre for cancer cases from the south-western part of Zimbabwe (until 1980, Rhodesia), including the provinces of Matabeleland (North and South), Masvingo, and Midlands. New cases of cancer were notified from all hospital wards and departments; case notes with a diagnosis of cancer or suspected cancer were sent to the registry on discharge or death. Results from the registry for 1963–1967 were published in Cancer Incidence in Five Continents (CI5) volumes II (2) and for 1968–1973 in volume III (3). The complete results for the 15-year period were published as a monograph (4), and in summary form by Parkin and colleagues (5). The activity of the registry was restarted by the Ministry of Health and Child Care in 2011 to strengthen the Zimbabwe National Cancer Registry. The registry results have been published for 2011–2013 in the monograph Cancer in sub-Saharan Africa II (6) and for 2013–2015 in Cancer in sub-Saharan Africa III (7). Here we compare the incidence rates in the Black (African) population of Bulawayo for the period 1963–1972 (during which registration was considered to be relatively complete) with those in the same population for the 5-year period 2011–2015. The changes observed illustrate the evolution of the cancer epidemic over a 50-year period, reflecting the general pattern of change in sub-Saharan Africa, as well as the results of factors specific to this population, including changes in occupational exposures, and the occurrence of the epidemic of human immunodeficiency virus (HIV)-AIDS. Materials and Methods The regional branch of the Zimbabwe National Cancer Registry is located in Mpilo Central Hospital (Bulawayo, Zimbabwe). Preinde- pendence (the period 1963–1977), the hospital served the Black African population only, and registration was carried out by a single cancer registrar, supervised by the Head of the Radiotherapy Centre. She collected data on all cancer cases entering the hospital (usually conducting personal interviews) as well as from the pathology depart- ment and the death register for the province. A detailed description of the methodology is in Skinner and colleagues (4), and a summary in Parkin and colleagues (5). Since 2013, the registry has had two full-time staff, supervised by the Head of the Radiotherapy Centre. The methods are described fully in Parkin and colleagues (7). Briefly, the main sources of information are from all hospitals and laboratories within the registration area, either publicly or privately owned, two private oncology clinics, the govern- ment pathology laboratory at Mpilo Central Hospital (Bulawayo, 1 Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom. 2 African Cancer Registry Network, Prama House, Oxford, United Kingdom. 3 International Agency for Research on Cancer, Lyon, France. 4 Radio- therapy Centre, Mpilo Central Hospital, Bulawayo, Zimbabwe. 5 Zimbabwe National Cancer Registry, Parirenyatwa Group of Hospitals, Harare, Zimbabwe. 6 Radiotherapy Centre, Parirenyatwa Group of Hospitals, Harare, Zimbabwe. Note: Supplementary data for this article are available at Cancer Epidemiology, Biomarkers & Prevention Online (http://cebp.aacrjournals.org/). Corresponding Author: Donald Maxwell Parkin, Nuffield Department of Population Health, University of Oxford, Old Road Campus, Oxford OX3 7LF, United Kingdom. Phone: 44-1865-3663; Fax: 44-1865-3985; E-mail: max.parkin@ndph.ox.ac.uk Cancer Epidemiol Biomarkers Prev 2021;30:867–73 doi: 10.1158/1055-9965.EPI-20-0669 Ó2021 American Association for Cancer Research. AACRJournals.org | 867 Downloaded from http://aacrjournals.org/cebp/article-pdf/30/5/867/3100879/867.pdf by guest on 16 June 2022