Heart Dosimetry is Correlated With Risk of Radiation Pneumonitis After Lung-Sparing Hemithoracic Pleural Intensity Modulated Radiation Therapy for Malignant Pleural Mesothelioma

PURPOSE

To determine clinically helpful dose-volume and clinical metrics correlating with symptomatic radiation pneumonitis (RP) in malignant pleural mesothelioma (MPM) patients with 2 lungs treated with hemithoracic intensity modulated pleural radiation therapy (IMPRINT).

METHODS AND MATERIALS

Treatment plans and resulting normal organ dose-volume histograms of 103 consecutive MPM patients treated with IMPRINT (February 2005 to January 2015) to the highest dose ≤50.4 Gy satisfying departmental normal tissue constraints were uniformly recalculated. Patient records provided maximum RP grade (Common Terminology Criteria for Toxicity and Adverse Event version 4.0) and clinical and demographic information. Correlations analyzed with the Cox model were grade ≥2 RP (RP2+) and grade ≥3 RP (RP3+) with clinical variables, with volumes of planning target volume (PTV) and PTV-lung overlap and with mean dose, percent volume receiving dose D (V_D), highest dose encompassing % volume V, (D_V), and heart, total, ipsilateral, and contralateral lung volumes.

RESULTS

Twenty-seven patients had RP2+ (14 with RP3+). The median prescription dose was 46.8 Gy (39.6-50.4 Gy, 1.8 Gy/fraction). The median age was 67.6 years (range, 42-83 years). There were 79 men, 40 never-smokers, and 44 with left-sided MPM. There were no significant (P≤.05) correlations with clinical variables, prescription dose, total lung dose-volume metrics, and PTV-lung overlap volume. Dose-volume correlations for heart were RP2+ with V_D (35 ≤ D ≤ 47 Gy, V₄₃ strongest at P=.003), RP3+ with V_D (31 ≤ D ≤ 45 Gy), RP2+ with D_V (5 ≤ V ≤ 30%), RP3+ with D_V (15 ≤ V ≤ 35%), and mean dose. Significant for ipsilateral lung were RP2+ with V_D (38 ≤ D ≤ 44 Gy), RP3+ with V₄₁, RP2+ and RP3+ with minimum dose, and for contralateral lung, RP2+ with maximum dose. Correlation of PTV with RP2+ was strong (P<.001) and also significant with RP3+.

CONCLUSIONS

Heart dose correlated strongly with symptomatic RP in this large cohort of MPM patients with 2 lungs treated with IMPRINT. Planning constraints to reduce future heart doses are suggested.

Detection of Recurrence Patterns After Wedge Resection for Early Stage Lung Cancer: Rationale for Radiologic Follow-Up

BACKGROUND

Wedge resection for selected patients with early stage non-small cell lung cancer is considered to be a valid treatment option. The aim of this study was to evaluate the recurrence patterns after wedge resection, to analyze the survival of patients under routine follow-up, and to recommend a follow-up regimen.

METHODS

A retrospective analysis was done of 446 consecutive patients between May 2000 and December 2012 who underwent a wedge resection for clinical stage I non-small cell lung cancer. All patients were followed up with a computed tomography scan with or without contrast. The recurrence was recorded as local (involving the same lobe of wedge resection), regional (involving mediastinal or hilar lymph nodes or a different lobe), or distant (including distant metastasis and pleural disease).

RESULTS

Median follow-up for survivors (n = 283) was 44.6 months. In all, 163 patients died; median overall survival was 82.6 months. Thirty-six patients were diagnosed with new primary non-small cell lung cancer, and 152 with recurrence (79 local, 45 regional, and 28 distant). There was no difference in the incidence of recurrence detection detected by computed tomography scans with versus without contrast (p = 0.18). The cumulative incidence of local recurrences at 1, 2, and 3 years was higher than the cumulative incidence for local, regional, and distant recurrences: 5.2%, 11.1%, and 14.9% versus 3.7%, 6.6%, and 9.5% versus 2.3%, 4.7%, and 6.4%, respectively. Primary tumor diameter was associated with local recurrence in univariate analysis.

CONCLUSIONS

Wedge resection for early stage non-small cell lung cancer is associated with a significant risk for local and regional recurrence. Long-term follow-up using noncontrast computed tomography scans at consistent intervals is appropriate to monitor for these recurrences.