Abstract
Purpose/objectiveLocal treatment options for patients with in-field non-small cell lung cancer (NSCLC) recurrence following conventionally fractionated external beam radiation therapy (CF-EBRT) are limited. Stereotactic body radiation therapy (SBRT) is a promising modality to achieve reasonable local control, although toxicity remains a concern.Materials/methodsPatients previously treated with high-dose CF-EBRT (≥59.4 Gy, ≤3 Gy/fraction) for non-metastatic NSCLC who underwent salvage SBRT for localized ultra-central in-field recurrence were included in this analysis. Ultra-central recurrences were defined as those abutting the trachea, mainstem bronchus, or esophagus and included both parenchymal and nodal recurrences. The Kaplan-Meier method was used to estimate local control and overall survival. Durable local control was defined as ≥12 months. Toxicity was scored per the CTC-AE v4.0.ResultsTwenty patients were treated with five-fraction robotic SBRT for ultra-central in-field recurrence following CF-EBRT. Fifty percent of recurrences were adenocarcinoma, while 35% of tumors were classified as squamous cell carcinoma. The median interval between the end of CF-EBRT and SBRT was 23.3 months (range: 2.6 – 93.6 months). The median CF-EBRT dose was 63 Gy (range: 59.4 – 75 Gy), the median SBRT dose was 35 Gy (range: 25 – 45 Gy), and the median total equivalent dose in 2 Gy fractions (EQD2) was 116 Gy (range: 91.3 – 136.7 Gy). At a median follow-up of 12 months for all patients and 37.5 months in surviving patients, the majority of patients (90%) have died. High-dose SBRT was associated with improved local control (p < .01), and the one-year overall survival and local control were 77.8% and 66.7% respectively in this sub-group. No late esophageal toxicity was noted, although a patient who received an SBRT dose of 45 Gy (total EQD2: 129.7 Gy) experienced grade 5 hemoptysis 35 months following treatment.ConclusionsAlthough the overall prognosis for patients with in-field ultra-central NSCLC recurrences following CF-EBRT remains grim, five-fraction SBRT was well tolerated with an acceptable toxicity profile. Dose escalation above 35 Gy may offer improved local control, however caution is warranted when treating high-risk recurrences with aggressive regimens.
Highlights
The incidence of lung and bronchus cancer has been steadily decreasing in the United States, the disease is still responsible for more deaths per year than any other malignancy [1]
Twenty patients were treated with five-fraction robotic Stereotactic body radiation therapy (SBRT) for ultra-central in-field recurrence following conventionally fractionated external beam radiation therapy (CF-EBRT)
High-dose SBRT was associated with improved local control (p < .01), and the one-year overall survival and local control were 77. 8% and 66.7% respectively in this sub-group
Summary
The incidence of lung and bronchus cancer has been steadily decreasing in the United States, the disease is still responsible for more deaths per year than any other malignancy [1]. Survival rates for patients with locally advanced NSCLC reported in the literature are grim, with an estimated 5-year overall survival for stage IIIA and IIIB patients of 19% and 7% respectively according to the 2007 International Association for the Study of Lung Cancer (IASLC) database analysis [5]. According to the 2016 update of the IASLC database analysis, 5-year overall survival rates have soared over the past decade to 36% and 19% in stage IIIA and IIIB patients respectively [6]. While such a drastic improvement in 5-year overall survival for locally advanced patients must be taken with a degree of caution, these data are highly encouraging. The gravity of preventing morbid local failure may grow ever more paramount
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