Problems of cervical cancer screening programmes.

The feasibility of using an age-sex register as a basis for a cervical cancer screening programme was investigated in a London practice serving both inner city and suburban populations. Only about 25% of 810 women aged 35-59 years who had not recently been screened responded to an invitation to attend a practice well woman clinic for a cervical smear. Nearly 30% of the invitations were returned ;not known at this address' and there was no reply from the remaining 45%. A high proportion of incorrect addresses considerably reduces the effectiveness of a cancer screening programme based on an age-sex register covering an area with a mobile population and also makes it difficult to follow up women with abnormal smears adequately. Opportunistic screening remains essential and every effort should be made to encourage women to be responsible for their own cancer screening programmes.