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S64

I. J. Radiation Oncology

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● Biology ● Physics

Volume 66, Number 3, Supplement, 2006

The Impact of the PORT Meta-Analysis on the Use of Radiotherapy in Non-Small Cell Lung Cancer Patients Who Underwent Surgical Resection

J. Varlotto1, M. DeCamp1, A. Recht1, J. Flickinger2 Beth Israel Deaconess Medical Center, Boston, MA, 2University of Pittsburgh Cancer Institute, Pittsburgh, PA

1

Purpose/Objective(s): The Postoperative Radiotherapy(PORT) Meta-Analysis, published in 1998, found that postoperative radiotherapy decreased survival in patients with Stages I or II non-small cell lung cancer, though it resulted in a non-significant survival increase in patients with Stage III cancers. We investigated the use of radiotherapy in patients who underwent potentially curative resection before and after this publication. Materials/Methods: The incidence and correlates of the use of radiotherapy were retrospectively analyzed for 36,776 eligible patients included in the Surveillance, Epidemiology, and End Results data-base from 1992-1997 (Group A, 21056 patients) and 1999-2002 (Group B, 15720 patients). Results: Radiotherapy was given to 22.1% and 16.2% of patients in Groups A and B, respectively (p ⬍ 0.0001). The usage of pre-operative radiotherapy in Groups A and B(2.4% vs 2.5%) was not significantly different (p⫽0.638). There was a significant decline in percentage of patients receiving post-operative radiotherapy(19.2% Group A vs 10.4% Group B, p⬍0.0005). Radiation sequence unknown increased from 0.4%(Group A) to 3.2%(Group B) (p ⬍0.0005). The use of radiotherapy significantly decreased after 1998 for each subgroup defined by stage (I, II, IIIA, IIIB) or extent of resection (less than a lobectomy, lobectomy/bi-lobectomy, and pneumonectomy) (see Table; p⬍0.0005 in all cases). A logistic regression model revealed that factors correlating with the use of radiotherapy were the same in both Groups (younger patient age, Stage IIIA, surgery less than a lobectomy, larger tumor size, and higher tumor grade), except for race (other than black or white) also being a significant factor for Group B. Conclusions: Since the correlates of radiotherapy use in each time cohort were almost the same, we believe the statisticallysignificant decline in the use of radiotherapy in patients undergoing resection of lung cancer after 1998 directly reflects the impact of publication of the PORT Meta-Analysis.

Proportion of patients receiving radiotherapy

Group

StageI

Stage II

Stage IIIA

Stage IIIIB

⬍Lobectomy

lobectomy/ bi-lobectomy

Pneumonectomy

A B

6% 5%

43% 26%

59% 51%

48% 32%

19% 17%

21% 15%

35% 28%

Author Disclosure: J. Varlotto, None; M. DeCamp, None; A. Recht, None; J. Flickinger, None.

113

Multivariate and Subgroup Analysis of Radiotherapy in Surgical Patients With Non-Small Cell Lung Cancer From the SEER Database

J. C. Flickinger1, A. Recht2,3, M. DeCamp4,3, A. Fritz5, J. Varlotto2,3 Dept. of Radiation Oncology, U. of Pittsburgh School of Medicine, Pittsburgh, PA, 2Dept. of Radiation Oncology, Harvard Medical School, Boston, MA, 3Beth Israel Deaconess Medical Center, Boston, MA, 4Dept. of Surgery, Harvard Medical School, Boston, MA, 5Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD

1

Purpose/Objective(s): The utility of radiotherapy in non-small cell lung cancer patients undergoing surgical resection has been questioned in all stages. We sought to identify subgroups of these patients in whom radiotherapy is either beneficial or detrimental and why. Materials/Methods: We retrospectively analyzed data from 36,776 non-small cell lung cancer patients who underwent surgery included in the Surveillance, Epidemiology, and End Results data-base from 1992-2002. Pneumonectomy, lobectomy or bilobectomy, or ⬍lobectomy were performed in 15%, 75%, and 10%, with radiotherapy (XRT) administered to 18%, 18%, and 33% of these respective patients After excluding 8 patients with intraoperative radiotherapy, data were evenly split into an initial analysis group and a validation group. Factors identified significant in the initial analysis data set were tested for validation in the second data set. Results: Factors confirmed as significantly correlated with overall and disease-specific survival (DSS) included XRT (associated with poorer survival), treatment before 1998, stage, age, race, sex, number of positive lymph nodes, number of lymph nodes removed, lobectomy or bilobectomy, tumor diameter and grade. Radiotherapy was not significantly associated with deaths from heart disease, COPD/pneumonia, or second cancer in separate multivariate analyses. Analysis of subgroups split by both stage and number of positive lymph nodes found that XRT was significantly correlated with improved survival in all stages with ⱖ5 positive lymph nodes and in stage 3a patients with 1-4 lymph nodes (See figure), but with poorer survival in all stages with no positive lymph nodes. These associations with XRT remained significant (p⬍0.00225) in all subgroup multivariate models for overall survival and DSS controlled for all other significant prognostic factors.