Radiobiological modeling of radiation-induced acute rectal mucositis: A single-institutional study of cervical carcinoma
Balbir Singh1, Gaganpreet Singh2, Arun Singh Oinam3, Vivek Kumar4, Rajesh Vashistha5, Manjinder Singh Sidhu5, Maninder Singh5
1 Centre for Medical Physics, Panjab University, Chandigarh; Department of Radiation Oncology, Max Superspeciality Hospital, Bathinda, Punjab, India
2 Centre for Medical Physics, Panjab University; Department of Radiotherapy, PGIMER, Chandigarh, India
3 Department of Radiotherapy, PGIMER, Chandigarh, India
4 Centre for Medical Physics, Panjab University, Chandigarh, India
5 Department of Radiation Oncology, Max Superspeciality Hospital, Bathinda, Punjab, India
Arun Singh Oinam,
Department of Radiotherapy, PGIMER, Chandigarh - 160 012,
Source of Support: None, Conflict of Interest: None
Purpose: This study aimed to estimate the fitting parameters of sigmoidal dose–response (SDR) curve of radiation-induced acute rectal mucositis in pelvic cancer patients treated with Intensity Modulated Radiation Therapy (IMRT) for the calculation of normal tissue complication probability (NTCP).
Materials and Methods: Thirty cervical cancer patients were enrolled to model the SDR curve for rectal mucositis. The patients were evaluated weekly for acute radiation-induced (ARI) rectal mucositis toxicity and their scoring was performed as per Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. The radiobiological parameters, namely n, m, TD50, and γ50 were calculated from the fitted SDR curve obtained from the clinical data of cervical cancer patients.
Results: ARI toxicity for rectal mucosa in carcinoma of cervical cancer patients was calculated for the endpoint rectal mucositis. The n, m, TD50, and γ50 parameters from the SDR curve of Grade 1 and Grade 2 rectal mucositis were found to be 0.328, 0.047, 25.44 ± 1.21 (confidence interval [CI]: 95%), and 8.36 and 0.13, 0.07, 38.06 ± 2.94 (CI: 95%), and 5.15, respectively.
Conclusion: This study presents the fitting parameters for NTCP calculation of Grade 1 and Grade 2 ARI rectal toxicity for the endpoint of rectal mucositis. The provided nomograms of volume versus complication and dose versus complication for different grades of rectal mucositis help radiation oncologists to decide the limiting dose to reduce the acute toxicities.