Environmental risk factors for oesophageal cancer in Malawi: A case-control study

AIM

There is a high burden of oesophageal cancer in Malawi with dismal outcomes. It is not known whether environmental factors are associated with oesophageal cancer. Without knowing this critical information, prevention interventions are not possible. The purpose of this analysis was to explore environmental factors associated with oesophageal cancer in the Malawian context.

METHODS

A hospital-based case-control study of the association between environmental risk factors and oesophageal cancer was conducted at Kamuzu Central Hospital in Lilongwe, Malawi and Queen Elizabeth Central Hospital in Blantyre, Malawi. Ninety-six persons with squamous cell carcinoma and 180 controls were enrolled and analyzed. These two groups were compared for a range of environmental risk factors, using logistic regression models. Unadjusted and adjusted odds ratios and 95% confidence intervals (CI) were calculated.

RESULTS

Firewood cooking, cigarette smoking, and use of white maize flour all had strong associations with squamous cell carcinoma of the oesophagus, with adjusted odds ratios of 12.6 (95% CI: 4.2-37.7), 5.4 (95% CI: 2.0-15.2) and 6.6 (95% CI: 2.3-19.3), respectively.

CONCLUSIONS

Several modifiable risk factors were found to be strongly associated with squamous cell carcinoma. Research is needed to confirm these associations and then determine how to intervene on these modifiable risk factors in the Malawian context.

Cancer incidence in Blantyre, Malawi 1994-1998

In this paper, we report the first results from the population-based cancer registry for Blantyre district, Malawi, for the period 1994-1998. In this 5-year period, 1245 cases were recorded in males (an estimated age-standardized incidence of 92.0 per 100,000) and 1003 in females (an age standardised rate (ASR) of 88.8 per 105). The overall percentage of cases with histological verification was just 41.8%, indicating that case-finding outside the laboratory had been quite successful; nevertheless the rather low rates suggest possible underdiagnosis of cancer, as well as cases missed. As in other reports from the region, the contemporary pattern is dominated by Kaposi's sarcoma (KS) (55.2% cancers in men, 28% in women), the effect of the evolving epidemic of AIDS. The incidence of cervix cancer in women is high (ASR 26.2 per 105), and there are moderately high rates of oesophageal cancer (ASR 15.4 per 105 in men, 9.3 per 105 in women). In childhood, the cancer profile is dominated by Burkitt's lymphoma, which accounts for 42.4% of cancers; KS is now the second most frequent cancer of childhood.