This national cancer registry study demonstrated that cancer is an important public health problem and incidence was increasing in Malawi. Kaposi sarcoma, cancer of the cervix and cancer of the oesophagus were the major cause of the increasing trend. With high HIV prevalence of 10.6% [11
], the increase is Kaposi sarcoma and cervical cancer was in agreement with the findings from other studies [12
]. The active case finding was more extensive in this survey providing more complete national data than previously reported.
The introduction and scaling up of free HIV antiretroviral therapy (ART) programme and insecticide-treated bednets (ITN) in 2003 did not seem to have an impact on the trends of Kaposi sarcoma, cervical cancer and Burkitt's lymphoma respectively as suggested by studies from other countries [13
]. This could suggest that higher ART and ITN coverages are required to show impact on HIV and malaria related cancers than the current (2010) 65% coverage of estimated population in need of ART and 40% insecticide-treated bed net use in children under the age of five years [11
]. For cancer of the oesophagus, it was not known why the trend was increasing. High HIV prevalence was less likely because the association between cancer of the oesophagus and HIV/AIDS is not well established although both may be related to fumonisin, a mycotoxin found in maize [16
]. Increase in smoking, consumption of alcohol and maize contaminated with fumonisin could be some of the factors contributing to the increase in incidence of oesophageal cancer [7
]. Lung cancer, the world's most frequent cancer in males, is generally reported to be less common in sub-Saharan Africa [3
] although tobacco smoking is common with prevalence of at least 25% in men [7
]. The reasons for relatively low prevalence of lung cancer in the presence of high prevalence of tobacco smoking in sub-Saharan Africa are unknown. Under-reporting, misdiagnosis, competing high levels of HIV/AIDS related cancers could be the possible explanations [18
Our findings on the significance of gender and age differences for Kaposi sarcoma, cancer of oesophagus and non-Hodgkin lymphoma being more common in males than females, cancer of the oesophagus in people aged 60 years or more, and Kaposi sarcoma and non-Hodgkin lymphoma, in particular Burkitt's, being the most common cancers in children under 15 years of age were consistent with other studies [22
]. Two thirds (67.1%) of non-Hodgkin lymphoma cases were children aged less than 15 years old. As countries in sub-Saharan Africa implement universal coverage of ART and ITNs, there would be need to monitor the trends of HIV and malaria related cancers as one way of assessing other public health benefits of these interventions.
The Malawi Ministry of Health, through Sexual and Reproductive Health Unit, implemented a screen-and-treat programme for cervical cancer using visual inspection with acetic acid (VIA) approach. The programme started in 2004 and targeted women aged 30-50 years old. As of June 2011, there were a total of 81 health facilities providing cervical cancer services (50 VIA only, 29 VIA and cryotherapy and 2 VIA, cryotherapy, loop electrosurgical excision procedure (LEEP) and major surgery). Cumulatively, a total of 59,217 women were screened, 5,744 (9.7%) were VIA positive and 1,777 (3.0%) had suspected cervical cancer [26
]. This study demonstrated that 12.0% and 32.1% of cervical cancer cases were aged 20-29 years and 50 years or more respectively. This would suggest that the VIA Programme in Malawi could be missing at least 44% of women with cervical cancer. Data on population-based, age-specific prevalence of Human papillomavirus (HPV), the virus that causes cervical cancer is not available in Malawi. However, WHO estimates that the overall HPV prevalence is about 34% [27
]. Studies from other countries reported HPV prevalence in women having two peaks, one at 15-29 year age group and the other at 60-69 year age group [28
]. This, together with high HIV prevalence could be some of the reasons for cervical cancer occurrence in young and older age groups. Cervical cancer screening is the only established public health cancer screening programme in Malawi. Breast (mammography) and prostate (prostate-specific antigen test and digital rectal examination) cancer screening were available in only one private hospital. This private hospital participated in the study. Lung cancer was not routinely screened. Introduction of other cancer screening services in addition to cervical cancer in public health facilities could enhance early detection and treatment.
This study also revealed that only 18% of the cancer cases had laboratory verified diagnosis. Inadequate laboratory capacity (only one public and one private histology laboratory, all in Blantyre), long waiting time to get histology results, confidence of health workers in diagnosing some cancers clinically, in particular Kaposi sarcoma (the commonest cancer), late presentation of patients to health facility and lack of treatment, in particular, chemotherapy and radiotherapy could be some of the factors leading to low laboratory verified diagnosis. The low level of laboratory verified cases would suggest that the reported number of cancer cases was likely to be under-estimated because of under diagnosis and missing of cancer cases [21
]. Current WHO estimates suggest that every year there are at least 2,316 new cases of cervical cancer cases in Malawi [27
] while estimate from this study was 1,236. This illustrated that the reported number of registered new cervical cancer cases was only 53% of the actual problem at the community level. Some of the possible reasons for under-detection of cervical cancer cases could be low coverage of the screening programme (3.7% of the target group) and low specificity of VIA although it is the cost-effective screening method recommended for resource-limited settings and is comparable to Pap smear [27
]. Despite the under-reporting, population-based cancer registry is the cost-effective method of collecting comprehensive data on cancer that resource-poor countries in sub-Saharan Africa are being encouraged to establish [33
About half (52%) of registered new cancer cases (all types of cancer) were from the southern region with central and northern region accounting for 35% and 13% respectively. Population distribution was less likely to be the main reason as distribution was similar in the south and centre at 45% and 42% respectively [34
]. The extent of active case finding in this survey was similar in all the regions whereby as many health facilities as possible were visited. Availability of diagnostic services hence less specimen transport cost and waiting time for results, cancer registry office and high HIV prevalence (south 18%, centre 10%, and north 8%) in the southern region were likely to be some of the contributing factors [11
Data on lifestyles (tobacco smoking and alcohol consumption) and HIV status were not available. Some of the registers, particularly in public facilities were missing. These were the limitations of this study. These limitations apply to all studies that utilise available health facility data in general. Another limitation of this study was the refusal by three international research institutions to participate in this study. The reason for their refusal was that they had to seek clearance from their headquarters which was not granted. However, all the three international research institutions were housed within the public hospital and were recruiting cases from outpatient department or wards. In addition, all the institutions sent specimens to National Histopathology Laboratory which participated in this study. It was therefore less likely that non-participation of these three international research institutions had significant effect on the results as most of cases were likely to be captured either from public hospital registers where cases were first registered or from histology laboratory where specimens were sent or both. The use of clinical diagnosis only, cancer screening tests such as VIA and prostate specific antigen (PSA) have their own limitations but these limitations were beyond this study. This study only collected and analysed data that were already there. Nevertheless, the comprehensive analysis of the burden of cancer and its challenges demonstrated by this study provided local evidence that could be used to inform policies, strategies and interventions for prevention and control of cancer in Malawi, eastern and southern African region.