Size and Predictive Factors of Microscopic Tumor Extension in Locally Advanced Non-Small Cell Lung Cancer.

PURPOSE: Radiation therapy for locally advanced non-small cell lung cancer (NSCLC) should treat the whole tumor, including its microscopic extensions, and protect adjacent organs at risk as much as possible. The aim of our study is to evaluate the size of microscopic tumor extension (MEmax) in NSCLC, and search for potential predictive factors. METHODS AND MATERIALS: We retrospectively selected 70 patients treated with postoperative radiation therapy for a NSCLC with N2 nodal status, then 34 additional patients operated for a squamous cell lung cancer with N1 or N2 nodal status. On the digitized slides originating from the resected tumors of these 104 patients, we outlined the border of the tumor, as seen with the naked eye. We then searched for microscopic tumor extension outside of these borders with a magnification as high as 40 × and measured the maximum size of MEmax. RESULTS: The median MEmax in the whole cohort was 0.85 mm (0-9.95). The MEmax was <5.3 mm in 95% of adenocarcinomas (6.5 mm in the subgroup without neoadjuvant chemotherapy) and <3.5 mm in 95% of squamous cell carcinomas (3.7 mm in the subgroup without neoadjuvant chemotherapy). After multivariate analysis, the factors associated with the size of MEmax were vascular invasion (P = .0002), histologic type, with a wider MEmax for adenocarcinomas in comparison with squamous cell carcinomas (P = .002), tumor size, which was inversely related with the size of MEmax (P = .024), and high blood pressure (P = .03). Macroscopic histologic tumor size was well correlated with both radiologic tumor size on a mediastinal setting computed tomography (correlation coefficient of 0.845) and on a parenchymal setting computed tomography (correlation coefficient of 0.836). CONCLUSIONS: The clinical target volume margin, accounting for microscopic tumoral extension, could be reduced to 7 mm for adenocarcinomas and 4 mm for squamous cell carcinomas.

Tumor burden and location as prognostic factors in patients treated by iodine seed implant brachytherapy for localized prostate cancers.

BACKGROUND: Iodine seed implant brachytherapy is indicated for low risk and selected favorable intermediate risk prostate cancers. A percentage of positive biopsies > 50% is usually considered as a contra-indication, and the tumor location could also influence the treatment efficacy. We studied the association of the percentage of positive biopsy cores, and tumor location, with progression-free survival. METHODS: Among the 382 patients treated at our center by permanent implant iodine seed brachytherapy for a localized prostate cancer between 2006 and 2013, 282 had accessible detailed pathology reports, a minimum follow-up of 6 months, and were included. Progression was defined as a biochemical, local, nodal, or distant metastatic relapse. We studied cancer location on biopsies (base, midgland or apex of the prostate) and percentage of positive biopsy cores, as well as potential confounders (pre-treatment PSA, tumor stage, Gleason score, risk group according to D'Amico's classification modified by Zumsteg, adjunction of androgen deprivation therapy, and dosimetric data). RESULTS: Most patients (197; 69.9%) had a low risk, 67 (23.8%) a favorable intermediate risk, 16 (5.7%) an unfavorable intermediate risk, and 1 (0.3%) a high-risk prostate cancer. An involvement of the apex was found for 131 patients (46,5%), of the midgland for 149 (52,8%), and of the base for 145 (51,4%). The median percentage of positive biopsy cores was 17% [3-75%]. The median follow-up was 64 months [12-140]. Twenty patients (7%) progressed: 4 progressions (20%) were biochemical only, 7 (35%) were prostatic or seminal, 6 (30%) were nodal, and 3 (15%) were metastatic. The median time to failure was 39.5 months [9-108]. There were more Gleason scores ≥7 among patients who progressed (40% vs 19%; p = 0.042). None of the studied covariates (including tumor location, and percentage of positive biopsy cores), were significantly associated with progression-free survival. The risk group showed a trend towards an association (p = 0.055). CONCLUSIONS: Brachytherapy is an efficient treatment (5-year control rate of 93%) for patients carefully selected with classical criteria. The percentage and location of positive biopsies were not significantly associated with progression-free survival. A Gleason score ≥ 7 was more frequent in case of progression.