Prospective Validation of Dose Volume Constraints for Acute Gastrointestinal Toxicity in Patients Undergoing Adjuvant IMRT for Cervical Cancer

Acute hematological toxicity during post-operative bowel sparing image-guided intensity modulated radiation with concurrent cisplatin

OBJECTIVE

To report acute hematological toxicity (HT) in patients receiving post-operative bowel sparing intensity-modulated radiotherapy (IMRT) and cisplatin and its dosimetric predictors.

METHODS

Clinical database of Phase III trial (NCT01279135), that randomized patients to post-operative conformal or intensity modulated radiation therapy, was searched to select patient strata that received bowel sparing IMRT (50 Gy/25#/5 wks) and concurrent cisplatin (40 mg m^-2). Pelvic bone marrow (BM) was retrospectively delineated in two sets: whole bone (WB), and freehand (FH) inner cavity of bone. Dose volume histograms (DVH) of BM were obtained. Receiver operating characteristic (ROC) curve identified DVH thresholds that predicted for Grade≥ II HT with highest specificity. Univariate and multivariate analysis was performed.

RESULTS

Overall 75 patients received concurrent cisplatin. Grades I-V HT was observed in 38.7%, 42.7%, 14.7%, 0%, and 0% patients, respectively. Grade ≥ II leukopenia, neutropenia, anemia, and thrombocytopenia were observed in 26%, 40%, 26.5%, and 1.4% respectively. None of the HT resulted in treatment break. On univariate analysis, whole pelvis+ lumbar FH V30 >55% & V40>35%, whole pelvis WB and FH V40 > 35%, and lower pelvis WB and FH V40 >20% correlated for Grade ≥ II leucopenia and neutropenia. None of the BM dose volume constraints predicted for overall HT or neutropenia on multivariate analysis.

CONCLUSION

The IMRT arm of NCT01279135 (PARCER study) that employed strict bowel constraints had unintentional but desirable BM sparing. None of the BM subvolume DVH parameters could be validated on multivariate analysis.

ADVANCES IN KNOWLEDGE

The prospective study reports feasibility of bone marrow sparing with bowel sparing post-operative pelvic IMRT and concurrent chemotherapy for cervical cancer. The present study reports low incidence of hematological and gastrointestinal toxicity during post-operative chemoradiation with IMRT. As both whole bone and freehand pelvis BM contours predicted for HT, hence an easier method of whole bone contouring should continue to be used till further validation of more specific BM subvolumes becomes available. The study results highlight the need for further research into dose volume constraints during post-operative IMRT.

Cancer cervix: Establishing an evidence-based strategy, an experience of a tertiary care centre in India

Carcinoma cervix is a common cancer among Indian women. Evidence based management is essential for best practice in treatment of carcinoma cervix for its effective control. The current imaging system like CT, MRI and PET CT scans have contributed in identifying the patients for optimal treatment and delivering treatment accurately. For stages IB2 to IV, concurrent chemoradiation is advocated with improvement in overall survival proven with randomized trials. Brachytherapy is an integral part in the radiation treatment. Imaged-guided brachytherapy using MRI is desirable, however less expensive imaging modalities such as CT and ultrasonography has been evaluated. In special situation such as for HIV positive patients and patients with neuroendocrine tumors have role of radiotherapy. For further improvement in control of cancer, it is required to integrate basic research to answer clinically relevant questions.