Four years experience of the survey on quality control of lung cancer screening system in Japan

A survey about further work-up for cases with positive sputum cytology during lung cancer mass screening in Ishikawa Prefecture, Japan: a retrospective analysis about quality assurance of lung cancer screening

OBJECTIVE

In cancer screening programs, performing appropriate further work-up is essential. In order to elucidate whether the further work-up for the subjects with positive screening results by sputum cytology was performed appropriately, the present study was conducted as the first large-scale thorough survey in Japan.

METHODS

All of the lung cancer screening records from 2007 to 2012 in Ishikawa Prefecture were reviewed. Additional investigations about the further work-up were performed.

RESULTS

In total, 2 234 984 people were invited to undergo lung cancer screening, and 494 424 people participated in the screening. Of these, 25 264 people underwent sputum cytology, and 68 positive cases were identified. Three of these 68 cases did not undergo further work-up, and another three cases had already been diagnosed to have lung cancer. Forty-five of the remaining 62 cases did not have suspicious chest shadows, and bronchoscopic examinations were performed in 36 cases. Seventeen of these 36 cases were diagnosed as having cancer, whereas none of the nine cases who did not receive the examination was diagnosed (P = 0.038). A bronchoscopic examination was not performed due to other medical conditions in three cases, due to the patient's refusal in another three cases and in the remaining three cases, the reasons were unknown.

CONCLUSION

The participation rate for further work-up was very high. However, there are some issues to be resolved regarding the transmission of information. With our new registered hospital system, the quality assurance of our screening program will be improved.

Lung cancer screening and its efficacy

The efficacy of lung cancer screening should not be evaluated by the survival rate of lung cancer patients but by lung cancer mortality in a certain population because the survival rate can be greatly affected by several types of bias. Randomized controlled trials that were conducted during the 1970s and 1980s in Europe and the United States failed to prove the efficacy of lung cancer screening in decreasing the mortality rate; but recently the results of case-control studies in Japan have revealed that undergoing currently available screening decreases the risk of lung cancer deaths by 30%-60%. A system is now being created in Japan whereby the guidelines regarding cancer screening will continue to be updated. The preliminary reports concerning lung cancer screening using thoracic computed tomography revealed that not only the detection rate of lung cancer but also the survival rate of detected lung cancer patients were surprisingly high. However, the presence of some potential bias in these studies cannot be ignored; therefore, it is still unknown whether there is actual efficacy. Several randomized controlled trials are presently in progress overseas, but the interim results were not favorable. A randomized controlled trial should therefore immediately be started in Japan as well.