title: Time-dependent dose-response relation for absence of vaginal elasticity after gynecological radiation therapy.
abstract: To investigate the dose-response relation between the dose to the vagina and the patient-reported symptom 'absence of vaginal elasticity' and how time to follow-up influences this relation.
  
  
  
  The study included 78 long-term gynecological cancer survivors treated between 1991 and 2003 with external beam radiation therapy. Of those, 24 experienced absence of vaginal elasticity. A normal tissue complication model is introduced that takes into account the influence of time to follow-up on the dose-response relation and the patient's age. The best estimates of the dose-response parameters were calculated using Probit, Probit-Relative Seriality (RS) and Probit-time models. Log likelihood (LL) values and the Akaike Information Criterion (AIC) were used to evaluate the model fit.
  
  
  
  The dose-response parameters for 'absence of vaginal elasticity' according to the Probit and Probit-time models with the 68% Confidence Intervals (CI) were: LL=-39.8, D50=49.7 (47.2-52.4) Gy, γ50=1.40 (1.12-1.70) and LL=-37.4, D50=46.9 (43.5-50.9) Gy, γ50=1.81 (1.17-2.51) respectively.
  
  
  
  The proposed model, which describes the influence of time to follow-up on the dose-response relation, fits our data best. Our data indicate that the steepness of the dose-response curve of the dose to the vagina and the symptom 'absence of vaginal elasticity' increases with time to follow-up, while D50decreases.
authors.affiliation: Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden; Department of Oncology, Institute of Clinical Sciences, Division of Clinical Cancer Epidemiology, Sahlgrenska Academy, Gothenburg, Sweden. Electronic address: el.alevronta@gmail.com.
authors.forename: Eleftheria
authors.initials: E
authors.lastname: Alevronta
authors.affiliation: Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden; Department of Oncology and Department of Clinical and Experimental Medicine, Linköping University, Sweden.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Åvall-Lundqvist
authors.affiliation: Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden; Department of Hospital Physics, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Massoud
authors.initials: M
authors.lastname: Al-Abany
authors.affiliation: Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Tommy
authors.initials: T
authors.lastname: Nyberg
authors.affiliation: Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Lind
authors.affiliation: Department of Oncology, Institute of Clinical Sciences, Division of Clinical Cancer Epidemiology, Sahlgrenska Academy, Gothenburg, Sweden; Department of Oncology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Ann-Charlotte
authors.initials: AC
authors.lastname: Waldenström
authors.affiliation: Department of Oncology, Institute of Clinical Sciences, Division of Clinical Cancer Epidemiology, Sahlgrenska Academy, Gothenburg, Sweden; Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Sweden.
authors.forename: Caroline
authors.initials: C
authors.lastname: Olsson
authors.affiliation: Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden; Ersta Sköndal University College, Department of Health Care Sciences, Stockholm, Sweden.
authors.forename: Gail
authors.initials: G
authors.lastname: Dunberger
authors.affiliation: Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden; Department of Oncology, Institute of Clinical Sciences, Division of Clinical Cancer Epidemiology, Sahlgrenska Academy, Gothenburg, Sweden; Department of Oncology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Bergmark
authors.affiliation: Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden; Department of Oncology, Institute of Clinical Sciences, Division of Clinical Cancer Epidemiology, Sahlgrenska Academy, Gothenburg, Sweden.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Steineck
authors.affiliation: Department of Oncology-Pathology, Division of Medical Radiation Physics, Karolinska Institutet, Sweden.
authors.forename: Bengt K
authors.initials: BK
authors.lastname: Lind
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D004307:Dose-Response Relationship, Radiation; D004548:Elasticity / Q000528:radiation effects; D005260:Female; D005500:Follow-Up Studies; D005833:Genital Neoplasms, Female / Q000532:radiotherapy*; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D011336:Probability; D011832:Radiation Injuries / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects / Q000379:methods; D017741:Survivors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014621:Vagina / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000528:radiation effects*
keywords: Dose–response relation; Gynecological radiation therapy; NTCP; Time–response relation; Vaginal elasticity