US gynaecologists’ reasons for or against recommending ovarian cancer screening, their assumptions about why other gynaecologists recommend it, and their knowledge of concepts of cancer screening statistics
| Number of gynaecologists providing the respective response (%) | |||
| Screener n=231 | Non-screener n=170 | P value* | |
| Which of the following reasons influence your decision to recommend/not recommend ovarian cancer screening to average-risk women? | |||
| Reduced ovarian cancer mortality due to the screening | 106 (45.9) | 41 (24.1) | <0.001 |
| Reduced ovarian cancer incidence due to the screening | 79 (34.2) | 23 (13.5) | <0.001 |
| Concerns about the screening’s harms (eg, false alarms, overdiagnosis) | 48 (20.8) | 157 (92.4) | <0.001 |
| Fear of litigation if no screening is done and cancer develops later on | 155 (67.1) | 78 (45.9) | <0.001 |
| Screening is financially lucrative | 8 (3.5) | 9 (5.3) | 0.454 |
| Current guideline recommendations of accredited medical associations | 41 (17.7) | 149 (87.6) | <0.001 |
| Expectation of patients to offer everything in the fight against cancer | 163 (70.6) | 13 (7.6) | <0.001 |
| In your opinion, which of the following reasons contribute to your colleagues recommending ovarian cancer screening to average-risk women? | |||
| Reduced ovarian cancer mortality due to the screening | 107 (46.3) | 30 (17.6) | <0.001 |
| Reduced ovarian cancer incidence due to the screening | 59 (25.5) | 26 (15.3) | 0.059 |
| Concerns about the screening’s harms (eg, false alarms, overdiagnosis) | 39 (16.9) | 7 (4.6) | <0.001 |
| Fear of litigation if no screening is done and cancer develops later on | 121 (52.4) | 94 (61.4) | 0.093 |
| Screening is financially lucrative | 33 (14.3) | 74 (43.5) | <0.001 |
| Current guideline recommendations of accredited medical associations | 44 (19.0) | 12 (7.2) | 0.003 |
| Expectation of patients to offer everything in the fight against cancer | 167 (72.3) | 72 (42.4) | <0.001 |
| Knowledge of concepts of cancer screening statistics:which of the following proves that a cancer screening test saves lives from cancer death? | |||
| Increased 5-year survival rate in the screened group (incorrect)† | 169 (73.2) | 106 (62.4) | 0.023 |
| Increased incidence of cancer in screened group (incorrect)‡ | 111 (48.1) | 33 (19.4) | <0.001 |
| Detection of more early-stage cancers in the screened group (incorrect)§ | 152 (65.8) | 73 (42.9) | <0.001 |
| Reduced mortality rate in the screened group (correct)¶ | 184 (79.7) | 137 (80.6) | 0.900 |
*P values are derived from χ2 analysis.
†5-year survival in the screening group always increases because detection by screening (rather than later detection by symptoms) advances the time of diagnosis, known as lead time. Thus, the 5-year survival rate with screening can be better regardless of whether or not the screening test actually saves lives.
‡A screening test is only effective if the additional number of detected cancer cases translates into prevented cancer deaths. Simply detecting more cases of cancer cases in the screening group as compared with the non-screening group without a reduction in cancer mortality suggests the occurrence of overdiagnosis and overtreatment.
§Detecting more early-stage cancer cases in the screening group as compared with the non-screening group is also no proof that the cancer screening works if there is no equivalent reduction in cancer mortality. If finding more cancers earlier and therefore starting treatment earlier is indeed effective, then cancer mortality should also be reduced in the screening group.
¶Reduced mortality within the screening group in a randomised trial is the only valid evidence that lives are saved due to the screening. The reason for this is the way in which mortality rates are calculated. Whereas the calculation of survival rates is based only on those people diagnosed with cancer, the calculation of mortality rates is based on all people in the study arms, which makes the statistic robust against biases such as lead time bias.