Objective: (1) To compute the frequencies and peak age incidences of epithelial cell abnormalities (ECA) of uterine cervix in a cytology-based screening programme and (2) to analyze the comparative frequencies of squamous intraepithelial lesions (SIL) and malignancies in age groups <40 and > or =40 years, in order to assess the implications for screening protocol in resource limited settings.
Study design: Pap smears form 29,475 women were cytologically screened over a 4-year period as a part of hospital-based screening programme. The frequencies, peak age incidences and mean age of various ECA detected were computed. The data was further stratified in to age groups <40 (Gp 1) and > or =40 (Gp 2) and comparative profile of the lesions was analyzed.
Results: On cytologic screening of the smears 5.6% ECA were detected. Atypical squamous cells-undetermined significance (ASC-US) and low grade SILs (LSIL) were diagnosed more frequently in Gp 1 (p<0.001) while atypical glandular cells (AGC) and malignancies were more significantly more frequent in Gp 2 (p<0.001). The frequency of HSIL was similar in the two groups. The SILs predominated in the fourth decade while the malignant lesions were most frequent in age >50 years. The mean age for LSIL and HSIL was 34.7 and 37.7 years, respectively, while for malignancy it was 51.8 years thus corroborating the hypothesis that a prolonged latent phase exists between the precursor lesions and the onset of invasive cancer.
Conclusions: Since the goal of any screening programme should be to pick up majority of the precursor lesions and not frank cancers, it is desirable to initiate screening before 40 years of age. The WHO recommendation of once in a life time screening between 35 and 40 years of age seems appropriate for resource limited settings like ours.