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R.M. Macrae
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ORAL 20 - Chemoradiotherapy (ID 124)
- Event: WCLC 2015
- Type: Oral Session
- Track: Treatment of Locoregional Disease – NSCLC
- Presentations: 1
- Moderators:G. Blumenschein, J.Y. Chang
- Coordinates: 9/08/2015, 10:45 - 12:15, 201+203
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ORAL20.06 - Outcomes of Intensity Modulated and 3D-Conformal Radiotherapy for Stage III Non-Small Cell Lung Cancer in NRG Oncology/RTOG 0617 (ID 938)
10:45 - 12:15 | Author(s): R.M. Macrae
- Abstract
Background:
Intensity modulated radiation therapy (IMRT) has the potential to improve target coverage and spare toxicity in locally-advanced non-small cell lung cancer (NSCLC). However, the effect of IMRT on outcomes for NSCLC has not previously been assessed in a large prospective cooperative group clinical trial.
Methods:
A secondary analysis was performed in patients with stage III NSCLC in NRG/RTOG 0617, a randomized phase III comparison of standard-dose (60 Gy) versus high-dose (74 Gy) chemoradiotherapy +/- cetuximab. Radiotherapy (RT) technique was stratified by IMRT and 3D-conformal radiotherapy (3D-CRT). Baseline prognostic and RT dosimetric parameters were compared between IMRT and 3D-CRT after adjusting for RT dose levels and cetuximab use. The prognostic value of RT technique with respect to toxicity and efficacy was assessed through multivariate logistic regression (MVA) and Cox proportional hazards model after controlling for RT dose level, cetuximab use and other factors.
Results:
Of the 482 eligible patients treated with RT, 53% and 47% were treated with 3D-CRT and IMRT, respectively. The IMRT group had more stage IIIB (38.6 vs. 30.3%, P = 0.056), larger PTVs (mean 486 vs. 427 mL, P = 0.005), and larger PTV:lung ratio (mean 0.15 vs. 0.13, P = 0.013). In spite of larger PTV volumes, IMRT was associated with lower lung V20 (P = 0.08), and lower heart doses (V5, V20, V40) than 3D-CRT. In turn, IMRT was associated with a lower rate (3.5 versus 7.9%) of Grade 3+ pneumonitis (P = 0.0653). On MVA, the lung V20 significantly predicted grade 3+ pneumonitis, while the lung V5 and mean lung doses did not. Larger heart V40 was associated with worse OS (HR=1.013, P < 0.001), and the heart V40 was significantly lower in patients treated with IMRT. Patients treated with IMRT were also more likely (37 versus 29%) to receive full doses of consolidative chemotherapy (P = 0.05).
Conclusion:
Although IMRT was used to treat larger and less favorable tumors in RTOG 0617, it was associated with reduced risk of Grade 3+ pneumonitis and higher likelihood of receiving full doses of consolidative chemotherapy. The heart V40, shown to be highly prognostic for survival, can be substantially reduced with IMRT compared to 3D-CRT.
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P1.07 - Poster Session/ Small Cell Lung Cancer (ID 221)
- Event: WCLC 2015
- Type: Poster
- Track: Small Cell Lung Cancer
- Presentations: 1
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.07-007 - Prophylactic Cranial Irradiation in Extensive Stage Small Cell Lung Cancer: The Ottawa Hospital Experience (ID 1446)
09:30 - 17:00 | Author(s): R.M. Macrae
- Abstract
Background:
The role of radiation has been investigated in extensive stage small cell lung cancer (ES-SCLC) in two-fold: prophylactic cranial irradiation (PCI) and consolidative radiotherapy. A randomized control trial was published in 2007 (Slotman) which showed benefits for PCI in median survival and decreased cumulative risk of symptomatic brain metastases. We conducted a retrospective study to evaluate the uptake of PCI at The Ottawa Hospital (TOH) for ES-SCLC and its impact on time to brain metastasis and survival. TOH is the sole provider of cancer services for a population of 1.3 million.
Methods:
The medical records of 605 patients (206 limited stage, 399 extensive stage) with small cell lung cancer between Jan. 1, 2005 and Dec. 31, 2011 were reviewed. The cumulative incidence of brain metastases and cumulative proportion surviving was estimated using the Kaplan–Meier method comparing patients receiving PCI or not. Differences between the groups with covariates including age, gender, smoking status, ECOG score, extrathoracic involvement, and response to chemotherapy were analyzed using t-test.
Results:
158 out of 399 ES-SCLC patients (39.6%) had no brain metastases at diagnosis, received chemotherapy, and had a partial or complete response. Of the 158 patients with these criteria, 69 patients received PCI and 89 did not. 90 patients had brain metastasis on diagnosis, and 151 patients were not eligible or had no response/progression to chemotherapy. On multivariate analysis, the only statistically significant predictors of overall survival were initial performance status and use of PCI. Using t-test, only partial vs. complete response to chemotherapy was found to be significantly different between the PCI and no PCI groups. There was a statistically significant difference in survival (p= 0.0021) and time to brain metastasis curves (p = 0.00029). Median survival for PCI and non-PCI groups was 14.0 and 8.2 months respectively. Median time to brain metastasis was 18.0 and 9.0 months respectively. There was no significant difference in incidence of brain metastases (40.6% vs. 43.8%) in either group. With regards to uptake of PCI for ES-SCLC at The Ottawa Hospital, 24.2% (16/66) of patients before Jan. 1, 2008 were treated with PCI compared to 57.6% (53/92) after 2008. Figure 1
Conclusion:
PCI in the setting of at least partial response to chemotherapy was found to have a survival benefit and prolongation of time to brain metastasis. This has corresponded with an increased uptake of PCI at The Ottawa Hospital since publication of the EORTC 22993-08993 in 2007.
