Table 1 Response and participation rates of childhood cancer survivors and sister controls in the DCOG LATER-VEVO study*
| Â | Survivors | sister controls |
|---|---|---|
Invited | 1611 | 429 |
 Response received (responders) | 1215 (75%) | 333 (78%) |
 No response received (non-responders) | 396 (25%) | 96 (22%) |
Responders | Â | Â |
 Participants |  |  |
  Questionnaire only | 306 (19%) | 96 (22%) |
  Questionnaire and blood sample | 126 (8%) | 43 (10%) |
  Questionnaire, blood sample and transvaginal ultrasound | 509 (32%) | 174 (41%) |
 Non-participants | 274 (17%) | 20 (5%) |