title: Dosimetric risk estimates of radiation-induced malignancies after intensity modulated radiotherapy.
abstract: BACKGROUND
  The increasing popularity of intensity-modulated radiotherapy (IMRT) stems from its ability to generate a more conformal plan than hitherto possible with conventional planning. As a result, IMRT is in widespread use across diverse indications. However, the inherent nature of IMRT delivery makes it monitor unit inefficient and leads to increased normal tissue integral dose. This in turn may result in an increased risk of radiation-induced second malignancies.
  
  
  OBJECTIVE
  To calculate the risk of second malignancy post-IMRT.
  
  
  METHODS
  Observational study in a tertiary care institute.
  
  
  METHODS
  Eighteen previously untreated patients with head and neck cancers (n = 10) and prostate cancer (n = 8) were selected. In these patients, selected infield organs around the planning target volume were contoured, viz. brain and thyroid in patients with head and neck cancer and bladder, rectum and small intestine in patients with carcinoma prostate. The estimates of radiation-induced malignancies in these organs and the whole of the body were derived using the concept of Organ Equivalent Dose.
  
  
  METHODS
  Descriptive statistics (SPSS version 12).
  
  
  RESULTS
  The modal estimated incidence of radiation-induced malignancies was 129.87, 1.4, 0.10, 3.42, 7.789 and 129.85 per 10,000 person-years for the brain, thyroid, bladder, rectum, small intestine and whole body respectively.
  
  
  CONCLUSIONS
  The estimated risk of radiation-induced malignancies in the thyroid and rectum was similar to the available literature, while the risk for bladder carcinomas was lower than that reported. However, the calculated risk of radiation-induced tumors of the brain was more than that reported with conventional radiation therapy. We propose that estimation of the risk of radiation-induced malignancies should be a part of the plan evaluation process and special care should be taken before using this modality in young patients with benign tumors in the head and neck region.
authors.affiliation: Department of Radiotherapy and Regional Cancer Center, Post Graduate Institute of Medical Education and Research, Chandigarh - 160 012, India. vijaypgi@gmail.com
authors.forename: Vijay M
authors.initials: VM
authors.lastname: Patil
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kapoor
authors.forename: Santam
authors.initials: S
authors.lastname: Chakraborty
authors.forename: Sushmita
authors.initials: S
authors.lastname: Ghoshal
authors.forename: Arun S
authors.initials: AS
authors.lastname: Oinam
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Sharma
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000532:radiotherapy; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology / Q000209:etiology*; D016609:Neoplasms, Second Primary / Q000453:epidemiology / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage