R. Murata

Clinical outcomes of stereotactic body radiotherapy for stage I non-small cell lung cancer using different doses depending on tumor size

BackgroundThe treatment schedules for stereotactic body radiotherapy (SBRT) for lung cancer vary from institution to institution. Several reports have indicated that stage IB patients had worse outcomes than stage IA patients when the same dose was used. We evaluated the clinical outcomes of SBRT for stage I non-small cell lung cancer (NSCLC) treated with different doses depending on tumor diameter.MethodsBetween February 2004 and November 2008, 124 patients with stage I NSCLC underwent SBRT. Total doses of 44, 48, and 52 Gy were administered for tumors with a longest diameter of less than 1.5 cm, 1.5-3 cm, and larger than 3 cm, respectively. All doses were given in 4 fractions.ResultsFor all 124 patients, overall survival was 71%, cause-specific survival was 87%, progression-free survival was 60%, and local control was 80%, at 3 years. The 3-year overall survival was 79% for 85 stage IA patients treated with 48 Gy and 56% for 37 stage IB patients treated with 52 Gy (p = 0.05). At 3 years, cause-specific survival was 91% for the former group and 79% for the latter (p = 0.18), and progression-free survival was 62% versus 54% (p = 0.30). The 3-year local control rate was 81% versus 74% (p = 0.35). The cumulative incidence of grade 2 or 3 radiation pneumonitis was 11% in stage IA patients and 30% in stage IB patients (p = 0.02).ConclusionsThere was no difference in local control between stage IA and IB tumors despite the difference in tumor size. The benefit of increasing the SBRT dose for larger tumors should be investigated further.

Estimation of Errors Associated With Use of Linear-Quadratic Formalism for Evaluation of Biologic Equivalence Between Single and Hypofractionated Radiation Doses: An In Vitro Study

PURPOSE To investigate the reliability of the linear-quadratic (LQ) formalism and the magnitude of errors associated with its use in assessing biologic equivalence between single, high radiation doses and hypofractionated radiation doses. METHODS AND MATERIALS V79 and EMT6 single cells received single doses of 2-12 Gy or two or three fractions of 4 or 5 Gy, each at 4-h intervals. Single and fractionated doses to actually reduce the cell survival to the same level were determined by a colony assay. The alpha/beta ratio was obtained from the cell survival curves. Using the alpha/beta ratio and the LQ formalism, equivalent single doses for the hypofractionated doses were calculated. They were then compared with the actually determined equivalent single doses for the hypofractionated doses. The V79 spheroids received single doses of 5-26 Gy or two to five fractions of 5-12 Gy at 2 or 4-h interval, and then were assayed for cell survival. Next, equivalent single doses for the hypofractionated doses were determined, as were done for the single cells. RESULTS The alpha/beta ratio was 5.1 Gy for the V79 single cells and 0.36 Gy for EMT6. In V79, the equivalent single doses for the hypofractionated doses calculated using the LQ formalism were 12-19% lower than the actually measured biologically equivalent single doses. In the EMT6 cells, this trend was also seen, but the differences were not significant. In the V79 spheroids, the calculated doses were 18-30% lower than the measured doses. CONCLUSION Conversion of hypofractionated radiation doses to single doses using the LQ formalism could underestimate the effect of hypofractionated radiation by < or =30%.

Correlation between the serum KL-6 level and the grade of radiation pneumonitis after stereotactic body radiotherapy for stage I lung cancer or small lung metastasis.

0167-8140/

Radiotherapy for hilar or mediastinal lymph node metastases after definitive treatment with stereotactic body radiotherapy or surgery for stage I non-small cell lung cancer

see front matter 2011 Elsevier Irelan doi:10.1016/j.radonc.2011.05.031 ⇑ Corresponding author. Address: Department of Ra sity Graduate School of Medical Sciences, 1 Kawasu Nagoya 467-8601, Japan. E-mail address: h-iwa-ncu@nifty.com (H. Iwata). Serum levels of a sialylated carbohydrate antigen KL-6, a marker for interstitial pneumonitis, were serially measured before and after stereotactic body radiotherapy (SBRT) for lung tumors. It was suggested that KL-6 levels before and after SBRT would help to predict the occurrence of P Grade 2 radiation pneumonitis. 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 101 (2011) 267–270

Compatibility of the Linear-Quadratic Formalism and Biologically Effective Dose Concept to High-Dose-Per-Fraction Irradiation in a Murine Tumor

PURPOSE Management of regional lymph node (LN) recurrence is an important issue in definitive treatment of non-small cell lung cancer (NSCLC). We evaluated clinical outcomes of conventional radiotherapy for hilar or mediastinal LN metastases developing after stereotactic body radiotherapy (SBRT) or surgery for stage I NSCLC. METHODS AND MATERIALS Between 2004 and 2008, 26 patients with hilar or mediastinal LN metastases without local recurrence and distant metastasis after SBRT (n = 14) or surgery (n = 12) were treated with conventional radiotherapy. Twelve of the 14 post-SBRT patients (86%) were judged medically inoperable at the time of SBRT. All patients were treated to the hilum and mediastinum with conventional daily fractions of 2.0 Gy (n = 25) or 2.4 Gy (n = 1). The median total dose for treating metastatic LN was 60 Gy (range, 54-66 Gy) for the post-SBRT patients and 65 Gy (range, 60-66 Gy) for the post-surgery patients. Only 1 of the 14 post-SBRT patients and 8 of the 12 post-surgery patients received chemotherapy. RESULTS For all 26 patients, the overall and cause-specific survival rates at 3 years from radiation for LN metastases were 36% and 51%, respectively (14% and 39%, respectively, for the 14 post-SBRT patients and both 64% for the 12 post-surgery patients). Three of the SBRT patients were alive at 35 to 43 months with (n = 2) or without (n = 1) further recurrence, and 4 of the post-surgery patients were alive at 36 to 62 months with (n = 2) or without (n = 2) further recurrence. The incidence of ≥grade 2 pulmonary toxicity was 49% at 1 year (53% for post-SBRT patients and 44% for post-surgery patients). A grade 5 pulmonary toxicity was observed in 1 of the post-SBRT patients. CONCLUSIONS Conventional radiotherapy could successfully salvage LN relapses after SBRT as well as after surgery in 7 of 26 patients. Radiotherapy in this setting appears reasonably well tolerated.