Regular smear tests increase cervical cancer cure rate
MedWire News: Women with cervical cancer detected through cervical screening are more likely to be cured of the disease than those whose cancer is detected on the basis of symptoms, Swedish researchers report.
"Furthermore, women with symptomatic cancer who present within the recommended screening interval - that is, symptomatic interval cancers - have better chances of cure than women with symptomatic cancer with an overdue or absent smear test result," write Bengt Andrae (Karolinska Institute, Stockholm) and colleagues in the BMJ.
The improvement in cure rate was not attributable to lead time bias, but was partly due to screen-detected cancers being found at an earlier International Federation of Gynecology and Obstetrics (FIGO) stage than symptomatic ones, the researchers note.
In an extension of a nationwide audit of the Swedish cervical-screening program, Andrae and team investigated whether cervical screening improves cure of the disease or whether it merely increases the lead time until death.
They prospectively followed up all 1230 women with cervical cancer diagnosed during 1999-2001 in Sweden for an average of 8.5 years. Cure was defined in statistical terms as the point where relative survival (versus that expected in the general female population) reaches a plateau.
"This occurs when the women who are still alive no longer experience any excess mortality compared with the general female population. These women are considered statistically cured as they experience the same mortality as women of the same age without cancer," the team explains.
Five years after diagnosis, 440 (36%) women had died. Among them 373 (85%) had a recorded death from cervical cancer.
The cure proportion for women with screen-detected invasive cancer was 92% and for symptomatic women it was 66%, a statistically significant difference of 26%.
When FIGO stage at diagnosis was accounted for, the difference in cure between the groups decreased to 15%, but was still statistically significant.
Among symptomatic women, the cure proportion was significantly higher for those who had been screened according to recommendations (interval cancers; 74%) than among those overdue for screening (60%), a difference in cure proportion of 14%.
Cure proportions decreased with increasing FIGO stage, but were similar across all histopathologic types except for small cell carcinomas, which were associated with worse relative survival than other types.
"Our data imply that all women (regardless of previous participation) can be advised that screening will increase the likelihood of cure in case an invasive cancer is detected," Andrae and co-authors remark.
"More than three quarters of women who died from cervical cancer had no smear test taken within the recommended screening intervals, implying that the recommended intervals are adequate and that further reduction of incidence and mortality in cervical cancer should focus on reaching women who have not attended screening," they conclude.
By Laura Cowen