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National cancer registry

The national cancer registry of The Gambia was established in 1986 as part of the Gambia Hepatitis Intervention Study in collaboration with International Agency for Research on Cancer (IARC), the Medical Research Council (MRC) Laboratories of UK and the Government of Gambia at MRC, Banjul. It contributed data to the quinquennial IARC publication Cancer incidence in five continents in volumes VI and VIII^[1]. Cancer notification is voluntary, and registration of cases is done by passive and active methods. The principal sources of data are the medical records/registers in the hospitals in public and private sectors, pathology laboratories and other medical institutions. The registry covers the entire country of 11 300 km2 and caters to a population of about 1 million in 1997–1998 with a sex ratio of 1038 females to 1000 males. The average annual age-standardized incidence rate is 84 per 100 000 among males and 85 per 100 000 among females in 1997–1998. The top ranking cancers among males are liver, lung and prostate. Among females, the order is cervix, liver and breast.

Map: Map showing Gambia Click here to open map (PDF format)

The registry contributed data on survival from 6 cancer sites or types for the first time in this volume of the IARC publication on Cancer Survival in Africa, Asia, the Caribbean and Central America. A random sample of 150 cases of liver cancer and 275 cases of cervix cancer among the total incident cases was selected for this study. For the rest of the cancers, all incident cases have been included.

Data quality indices

The proportion of cases with histological confirmation of cancer diagnosis in this series is 25%, varying between 1% for liver cancer and 45% for non-Hodgkin lymphoma. The proportion of cases registered based on a death certificate only is negligible except for lung cancer. The exclusion of cases without any follow-up information is 25%, ranging from 1% in liver cancer to 34% in non-Hodgkin lymphoma. Thus, 54–82% of the total cases in different cancers are included in the estimation of the survival probability.

Table 1: Data quality indices - Proportion (%) of histologically verified and death certificate only cases, number and proportion of included and excluded cases by site, The Gambia, 1993-1997 cases followed-up until 1999 Click here to open table (PDF format) Click here to open comparative statistics by registry

Outcome of follow-up

Follow-up has been carried out predominantly by active methods. Cancer mortality information obtained from accessible death certificates in registration office is matched with the registry database. The vital status of the unmatched incident cases is then ascertained by repeated scrutiny of hospital records and house visits.

The closing date of follow-up was 31^st December 1999. The median follow-up varied from one month in stomach, liver and lung cancers to 6 months for cervix cancer. Complete follow-up at five years from the incidence date ranged between 81% in cancer of the lung and 98% for liver cancer. The bulk of the losses to follow-up generally occurred in the first year of follow-up.

Table 2: Number and proportion of cases with complete / incomplete follow-up and median follow-up (in months) by site, The Gambia, 1993-1997 cases followed-up until 1999 Click here to open table (PDF format) Click here to open comparative statistics by registry

Survival statistics

All ages and both sexes together

The 5-year relative survival was the highest in cancer of the lung (32%) followed by non-Hodgkin lymphoma (25%) and cervix (24%). The lowest survival rate was encountered with liver (3%) cancer and preceded by stomach (5%) cancer in the series.

The 5-year age-standardized relative survival (ASRS) probability for all ages together is either less than or similar to the corresponding unadjusted one for all the cancers except lung. The 5-year ASRS (0–74 years of age) is observed to be greater than or similar to the corresponding ASRS (all ages) for most cancers.

Table 3: Comparison of 1-, 3- and 5-year absolute and relative survival and 5-year age-standardized relative survival (ASRS) by site, The Gambia, 1993-1997 cases followed-up until 1999 Click here to open table (PDF format) Click here to open comparative statistics by registry

Sex

Table 4a: Site-wise number of cases, 5-year absolute and relative survival by sex, The Gambia, 1993-1997 cases followed-up until 1999 Click here to open table (PDF format) Click here to open comparative statistics by registry

Male

The highest 5-year relative survival was observed in lung cancer (29%). None of the breast cancer cases survived for 5 years from incidence date. The 5-year relative survival was notably higher among males than females in cancer of the stomach.

Female

The 5-year relative survival estimates for breast and cervix cancers were 11% and 24% respectively. None of the stomach cancer cases survived until 5 years from incidence date. Survival from non-Hodgkin lymphoma was noticeably higher among females than males.

Age group

The 5-year relative survival by age group was seen to fluctuate, with no definite pattern or trend emerging and no survivors in many age intervals.

Table 4b: Site-wise number of cases, 5-year absolute and relative survival by age group, The Gambia, 1993-1997 cases followed-up until 1999 Click here to open table (PDF format) Click here to open comparative statistics by registry

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References

1. Parkin DM, Whelan SL, Ferlay J and Storm H. Cancer Incidence in Five Continents, Vol I to VIII: IARC Cancerbase No. 7. IARCPress, Lyon, 2005.
   (link to CI5)