title: The impact of body mass index on radiotherapy technique in patients with early-stage endometrial cancer: a single-center dosimetric study.
abstract: OBJECTIVE
  We aimed to evaluate the impact of body mass index on radiotherapy (RT) technique in patients with early-stage endometrial cancer.
  
  
  METHODS
  Twenty-seven consecutive patients were included in the study and divided into 3 groups with respect to their body mass index (normal weight, 18.5-24.9 kg/m; overweight, 25-29.9 kg/m; obese, 30-39.9 kg/m). Treatment plans using field-in-field (FIF) and 3-dimensional conformal RT (3D-CRT) were compared for the doses in the planning target volume (PTV), organs-at-risk (OAR) volumes, dose homogeneity index, and monitor unit counts required for the treatment.
  
  
  RESULTS
  The FIF technique was superior to 3D-CRT with respect to the maximum and mean doses received by OAR and dose homogeneity index values. The subgroup analyses revealed that the maximum dose received by the right femur and the mean doses received by the rectum and bladder were significantly reduced only in obese patients (Ps = 0.021, 0.008, and 0.008, respectively). The FIF technique significantly reduced the PTV volumes irradiated with greater than 105% of the prescribed dose (P < 0.001). The volumes of bowel and bone marrow receiving more than the prescribed dose of 30 Gy were significantly reduced only in obese patients (Ps = 0.025 and 0.043, respectively). The volumes of bladder, bowel, and bone marrow receiving more than the prescribed dose of 45 Gy were significantly reduced in only obese patients (Ps = 0.011, 0.011, and 0.008, respectively).
  
  
  CONCLUSIONS
  Considering the lower maximum doses in OAR and PTV, we demonstrate the FIF technique to be more advantageous than 3D-CRT during adjuvant RT for early-stage endometrial cancer patients. This advantage is more prominent in obese patients. Therefore, FIF technique represents an effective pelvic RT treatment option for obese patients in clinics that do not have access to or prefer an alternative to intensity-modulated RT.
authors.affiliation: *Department of Radiation Oncology, Selcuk University; †Department of Radiation Oncology, Konya Training and Research Hospital; and ‡Department of Obstetrics and Gynecology, Selcuk University.
authors.forename: Guler
authors.initials: G
authors.lastname: Yavas
authors.forename: Cagdas
authors.initials: C
authors.lastname: Yavas
authors.forename: Ozlem Secilmis
authors.initials: OS
authors.lastname: Kerimoglu
authors.forename: Cetin
authors.initials: C
authors.lastname: Celik
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D016889:Endometrial Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D009765:Obesity / Q000503:physiopathology*; D058958:Organs at Risk / Q000528:radiation effects; D010386:Pelvic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011379:Prognosis; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D018714:Radiotherapy, Adjuvant; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated