title: Correlation between the Ki-67 proliferation index and response to radiation therapy in small cell lung cancer.
abstract: BACKGROUND
  In the breast cancer, the decision whether to administer adjuvant therapy is increasingly influenced by the Ki-67 proliferation index. In the present retrospective study, we investigated if this index could predict the therapeutic response to radiation therapy in small cell lung cancer (SCLC).
  
  
  METHODS
  Data from 19 SCLC patients who received thoracic radiation therapy were included. Clinical staging was assessed using the TNM classification system (UICC, 2009; cstage IIA/IIB/IIIA/IIIB = 3/1/7/8). Ki-67 was detected using immunostained tumour sections and the Ki-67 proliferation index was determined using e-Count software. Radiation therapy was administered at total doses of 45-60 Gy. A total of 16 of the 19 patients received chemotherapy.
  
  
  RESULTS
  Patients were divided into two groups, one with a Ki-67 proliferation index ≥79.77% (group 1, 8 cases) and the other with a Ki-67 proliferation index <79.77% (group 2, 11 cases). Following radiation therapy, a complete response (CR) was observed in six cases from group 1 (75.0%) and three cases from group 2 (27.3%). The Ki-67 proliferation index was significantly correlated with the CR rate (P = 0.05), which was significantly higher in group 1 than in group 2 (P = 0.04). The median survival time was 516 days for all patients, and the survival rates did not differ significantly between groups 1 and 2.
  
  
  CONCLUSIONS
  Our study is the first to evaluate the correlation between the Ki-67 proliferation index and SCLC tumour response to radiation therapy. Our findings suggest that a high Ki-67 proliferation index might represent a predictive factor for increased tumour radiosensitivity.
authors.affiliation: Department of Radiology, Nihon University School of Medicine, 30-1 Oyaguchi Kami-cho, Itabashi-ku, Tokyo, 173-8610, Japan. ishibashi.naoya@nihon-u.ac.jp.
authors.forename: Naoya
authors.initials: N
authors.lastname: Ishibashi
authors.affiliation: Department of Radiology, Nihon University School of Medicine, 30-1 Oyaguchi Kami-cho, Itabashi-ku, Tokyo, 173-8610, Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Maebayashi
authors.affiliation: Department of Radiology, Nihon University School of Medicine, 30-1 Oyaguchi Kami-cho, Itabashi-ku, Tokyo, 173-8610, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Aizawa
authors.affiliation: Department of Radiology, Nihon University School of Medicine, 30-1 Oyaguchi Kami-cho, Itabashi-ku, Tokyo, 173-8610, Japan.
authors.forename: Masakuni
authors.initials: M
authors.lastname: Sakaguchi
authors.affiliation: Department of Pathology, Nihon University School of Medicine, Itabashi-ku, Tokyo, 173-8610, Japan.
authors.forename: Haruna
authors.initials: H
authors.lastname: Nishimaki
authors.affiliation: Department of Pathology, Nihon University School of Medicine, Itabashi-ku, Tokyo, 173-8610, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Masuda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis*; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D008940:Mitotic Index; D011379:Prognosis; D012189:Retrospective Studies; D055752:Small Cell Lung Carcinoma / Q000473:pathology / Q000532:radiotherapy*; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen
keywords: Ki-67; Proliferation index; Radiation therapy; Response; Small cell lung cancer