Intraoperative I-125 vicryl mesh brachytherapy after sublobar resection for high-risk stage I non-small cell lung cancer

Abstract

To assess the feasibility and outcomes of vicryl mesh brachytherapy after sublobar resection in stage I non-small cell lung cancer (NSCLC) patients with poor pulmonary status. Between January 1997 and January 2003, 118 patients with Stage IA and IB (T1-2N0M0) NSCLC and poor cardiopulmonary reserve underwent sublobar resection accompanied by the placement of a permanent low-dose rate I-125 vicryl mesh brachytherapy implant. Mediastinal and hilar lymph node staging was routinely performed in all patients. After clear margins were obtained grossly and on frozen section, a single-plane I-125 implant was fashioned to deliver a prescribed dose of 85–129 Gy to a depth of 0.5 cm from the plane of the implant. I-125 seeds embedded in vicryl suture 1 cm apart were sewn onto a piece of polyglyconate mesh, and secured with surgical clips. The catheters were spaced 1.0–1.8 cm apart based upon specific seed activity using a standardized nomogram in order to obtain a homogeneous dose distribution. The implant was designed to straddle the staple line with a 2-cm margin. Implant size varied from 4.5x5.0 cm to 5.0x10.0 cm. The implant was introduced through the surgical incision and sutured to the visceral pleura. Follow-up orthogonal films or CTs were performed for dosimetric analysis. Three types of cancer recurrence after brachytherapy were assessed: (1) local recurrence was defined as recurrence within the radiation volume; (2) regional recurrence was defined as recurrence outside the radiation volume within the same lung, hilum, or mediastinum; and (3) distal recurrence was defined as progression of disease elsewhere. Kaplan-Meyer survival analyses were used to estimate the local control, cause-specific survival, and overall survival rates. Kolmogorov-Smirnov Z test and histogram were used to check the normality of the variables of interest. ANOVA and Mann-Whitney tests were used to examine the difference in the variables of interest by survival status. The average age of the study population was 71 years (range 50–89). Forty-seven percent were female (n = 55). Of the 118 patients, 71 were Stage IA while 47 were Stage IB. The mean preoperative forced expiratory volume in 1 second (FEV1) was 47% of the predicted volume. Eighty-seven patients underwent an open muscle-sparing thoracotomy and 31 patients underwent a video-assisted thoracoscopic surgery. The median total activity was 20 mCi (range 11–30). The median prescribed dose was 120 Gy (range 85–129). The median length of postoperative hospital stay was 7 days. With a median follow-up of 13 months (range 1–68 months), there were 4 local recurrences, 13 regional recurrences, and 9 distal recurrences. The estimated 5-year local control, cause-specific survival, and overall survival rates were 87%, 33%, and 18%, respectively. Five-year survival was 23% for T1 lesions and 10% for T2 lesions. Patients younger than 70 years of age had an estimated 5-year survival of 32%, while patients who were 70 and older had a 5-year survival of 11%. The average length of stay was 8 days for surviving patients while it was 16 days for those who died (p = NS). The mean FEV1 was 49% for surviving patients and 44% for the patients who died (p = NS). Vicryl mesh brachytherapy after sublobar resection for high-risk Stage I NSCLC patients is a feasible procedure, which results in an excellent local control rate (97%). A phase III randomized trial comparing sublobar resection alone with sublobar resection followed by vicryl mesh brachytherapy is currently underway to assess the clinical benefits of this procedure in a larger cohort of patients