Cervical Cancer in the Province of Manitoba: A 30-Year Experience

Abstract

ObjectivesThis study was undertaken to analyze trends in cervical cancer incidence by histological type and to track the survival rate in the province of Manitoba over a 30-year period. MethodsData from the Manitoba Cancer Registry (MCR) relating to all cases of cervical cancer that occurred between 1970 and 1999 in the province of Manitoba were analyzed to calculate incidence and survival rates according to histological subtype. ResultsOver this 30-year span, invasive cervical cancer was diagnosed in 1927 women, and carcinoma in situ was diagnosed in 10 006 women. Cervical cancer was the fifth most frequent cancer diagnosis for women in 1970, and by 1999 it had become the eleventh most frequent. The incidence rate for cervical cancer decreased from 21.6/100 000 women in 1970 to 8.8/100 000 women in 1999. The mortality rate for women with cervical cancer fell from 7.3/100 000 women in 1970 to 2.8 /100 000 women in 1999. Squamous cell carcinoma (SCC) was the most frequently diagnosed histologic subtype, but its incidence decreased from 1970 to 1999; the proportion of women with adenocarcinoma increased gradually over the same time from 7% to 22%. Survival rates were comparable in women with SCC and adenocarcinoma. In 1999, the incidence of cervical cancer in Manitoba was comparable to the Canadian rate. However, the mortality rate from cervical cancer was higher in Manitoba than in Canada overall. ConclusionThe incidence of cervical cancer and the incidence of cervical cancer-related deaths in Manitoba both dropped between 1970 and 1999. However, the incidence of cervical carcinoma in situ has increased steadily during the same period. These observations may reflect the effect of screening programs on the detection and treatment of cervical cancer precursors. Squamous cell carcinoma is still the most frequently diagnosed subtype of invasive cervical cancer, but the proportion of women with adenocarcinoma has increased. Deaths from cervical cancer showed a non-significant reduction over the study period.