1049PSpread of tumour and adverse events after modified radical hysterectomy for FIGO Stage IB1 cervical cancer patients with tumour diameter preoperatively estimated 2 cm or less: Japan Clinical Oncology Group trial (JCOG1101); exploratory analysis before primary analysis

Abstract Background A single-arm confirmatory trial (JCOG1101) is now on follow-up, which is to evaluate the efficacy of modified radical hysterectomy for FIGO Stage IB1 uterine cervical cancer patients (pts) with clinical maximal tumor diameter (MTD) estimated 2 cm or less (UMIN-CTR: UMIN000009726). It is needed to evaluate whether application of modified radical hysterectomy is feasible or not. Methods From Jan 2013 to Aug 2017, 240 pts were enrolled. We analyzed the data of 224 eligible pts who underwent modified radical hysterectomy to elucidate the relationship between clinical maximal tumor diameter (cMTD) and pathological MTD (pMTD), degree of tumor extension and adverse events (AEs). Results In 224 eligible pts, median pMTD was 1.5 cm (range, 0-4.5), and. pMTD were  Conclusions Though cMTD does not always correspond to pMTD on stage IB1 cervical cancer, low incidence of parametrial involvement and lymph node metastasis indicate that cMTD is useful as presurgical diagnosis. In addition, there was low frequency of AEs by modified radical hysterectomy, which was presumed to be less invasive than radical hysterectomy. Modified radical hysterectomy will be a standard surgery if the efficacy of modified radical hysterectomy in overall survival is confirmed by the primary analysis planned in 2022. Clinical trial identification UMIN-CTR: UMIN000009726, 08/Jan/2013. Legal entity responsible for the study JCOG (Japan Clinical Oncology Group). Funding National Cancer Center Research and Development Funds. Disclosure All authors have declared no conflicts of interest.