Lung Cancer

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TU_28_3591 - Pulmonary Function Trends Following Modern Radiation Therapy: Association of CTC Provider Assessment with Subacute and Late PFT Changes

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Pulmonary Function Trends Following Modern Radiation Therapy: Association of CTC Provider Assessment with Subacute and Late PFT Changes
A. C. Ferro, P. Han, R. Voong, T. R. McNutt, L. Chang, P. Lakshminarayanan, M. R. Bowers, L. Anderson, E. Desmarais, E. Honig, and R. K. Hales; Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD

Purpose/Objective(s): Pulmonary dosimetric parameters are correlated with physician reported common terminology criteria for adverse events (CTCAE) grade of radiation pneumonitis (RP). However, the correlation between CTCAE toxicity grade and pulmonary function test (PFT) changes is not well characterized. Additionally, long-term PFT outcomes are limited in the intensity-modulated radiotherapy (IMRT) era. In this report, we review CTCAE pulmonary data from lung cancer patients treated with IMRT and correlate them with 1) subacute PFTs change and 2) long term PFT changes. Materials/Methods: Between 05/2008 and 10/2015, lung cancer patients treated with IMRT with baseline and serial post-radiation pulmonary function tests (PFTS) were identified. Baseline patient characteristics, treatment details, and subacute and late toxicities (CTCAE and PFT changes) were recorded. CTCAE grade ≥ 2 RP was defined as symptomatic radiation changes requiring steroid medications within 12 months following radiation, unrelated to COPD or other medical comorbidities. Post-treatment PFTs were normalized to baseline PFTs and the relative declines were reported in < 6 month and >12 month time intervals, which were the time intervals representative of the subacute and chronic settings, respectively. Correlation between the development of Grade ≥ 2 RP and subacute (<6 months) and late changes (>12 months) in PFTs were assessed using a Student’s t-test. Results: Baseline and post-treatment PFTs were available for 188 patients. Concurrent chemotherapy was given in 87% of patients and 4% received induction chemotherapy. Baseline COPD (FEV1/FVC<0.7) was present in 53% of patients. CTCAE Grade ≥ 2 RP toxicity was recorded in 10.6% of patients. The mean time to development of RP was 4.4 ± 2.4 months. PFT changes stratified by the development of CTCAE Grade ≥ 2 RP are displayed in Table 1. In the subacute timeframe, patients who developed Grade ≥ 2 RP had statistically significant greater declines in DLCO (30% vs 14%, p= 0.002), FEV1 (11% vs 1%, p=0.03), and FVC (10% vs 0%, p= 0.049) compared to patients without RP reactions. In the chronic timeframe, statistically significant greater declines in FVC (11% vs +3%, p=0.01) remained while DLCO (25% vs 13% p-value: 0.13) and FEV1 (9% vs 0% p= 0.18) were no longer significant, but demonstrated a trend toward greater declines.

Conclusion: CTCAE Grade ≥ 2 RP toxicity correlated with declines in PFTs in the subacute timeframe, suggesting that CTCAE subacute toxicity may be an appropriate surrogate for PFT declines. Additionally, these data suggest there may be a correlation between subacute RP and late PFT decline.
Variable

Pre-RT (% Pred ± SD)

p

<6 months post RT

(Relative change ± SD)

p

12 months post RT (Relative change ± SD)

p

DLCO RP No RP 76 ± 26 80 ±19 NS RP No RP ↓30% ± 4% ↓14% ±2% 0.002 RP No RP ↓25% ± 7% ↓13% ±3% 0.13
FEV1 RP No RP 72 ± 23 75 ±21 NS RP No RP ↓11% ± 4% ↓1% ±2% 0.03 RP No RP ↓9% ± 6% ↓0% ±3% 0.18
FVC RP No RP 82 ± 20 87 ±18 NS RP No RP ↓10% ± 4% 0% ±2% 0.049 RP No RP ↓11% ± 4% ↑3% ±3% 0.01
 

Author Disclosure: A.C. Ferro: None. P. Han: None. R. Voong: Honoraria; Lung Cancer Research Foundation, Radiation Oncology Institute, ASCO. T.R. McNutt: Research Grant; Toshiba, Philips Radiation Oncology Systems, Elekta Oncology Systems. Patent/License Fees/Copyright; Sun Nuclear, Accuray-Tomotherapy. President Elect; AAPM-MAC. L. Chang: None. P. Lakshminarayanan: None. M.R. Bowers: None. E. Desmarais: None. R.K. Hales: Consultant; astraZeneca.

Adam Ferro, MD, MS

Disclosure:
Employment
Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine: Resident: Employee

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