Early response and local control of stage I non‐small‐cell lung cancer after stereotactic radiotherapy: difference by histology

Abstract

To investigate the possible influences of various factors on tumor response to radiation, regression speeds and long-term local control rates of primary adenocarcinoma and squamous cell carcinoma of the lung after stereotactic body radiotherapy were evaluated. Ninety-one patients (65 men and 26 women) with a median age of 76 years were serially examined using computed tomography at 2, 4 and 6 months after treatment. Tumor histology was adenocarcinoma in 62 patients and squamous cell carcinoma in 29 patients. The prescribed dose was 48 Gy in four fractions given twice a week for T1 tumors (≤3 cm) and 52 Gy in four fractions given twice a week for T2 tumors (3-5 cm). Tumor shrinkage speed and 3-year local control rates were similar between T1 and T2 tumors and between patients with normal pulmonary function and those with impaired function. Squamous cell carcinomas shrank faster than adenocarcinomas at 2 and 4 months after radiation, but mean relative tumor size at 6 months and local control rates at 3 years did not differ significantly between the two histologies. Tumors in patients with a higher hemoglobin level tended to shrink faster but the control rates were not different. It is concluded that, although squamous cell carcinoma shrinks faster than adenocarcinoma, the two types of lung cancer are of similar radiosensitivity in terms of longterm control rates. Radiosensitivity should not be evaluated by early tumor response. (Cancer Sci 2013; 104: 130-134) T he radiosensitivity of tumors varies with various tumorand patient-related factors. These include histology, grade of differentiation and size of tumors, and hemoglobin levels in patients. It is well known that small-cell carcinoma of the lung responds more quickly to radiation than other histological subtypes of lung cancer. In uterine cervical cancer treated with radiation, squamous cell carcinoma (SCC) is generally associated with a better prognosis than adenocarcinoma (AD); (1,2) such observations led many oncologists to assume that SCC is more radiosensitive than AD. (3,4) In addition, smaller tumors are generally more radiosensitive than larger ones.(5,6) Furthermore, extensive clinical data show that patients with a high hemoglobin level have a better prognosis than those with a low level following definitive radiotherapy of various cancers, (7)(8)(9)(10)(11) indicating that tumors in patients with a high hemoglobin level might be more radiosensitive than tumors in those with a low hemoglobin level. However, these observations mostly come from retrospective analyses of clinical data and have not been properly evaluated in a prospective study.Stereotactic body radiotherapy (SBRT) was introduced in the mid-1990s and has been performed in many institutions as a new treatment modality for stage I primary lung cancer. (12)(13)(14) Stereotactic body radiotherapy usually uses a few sessions of relatively high-dose irradiation. Therefore, if imaging studies are carried out serially after SBRT, shrinkage patterns and local control of irradiated tumors foll...

Changes in volume of stage I non-small-cell lung cancer during stereotactic body radiotherapy

“…Decrease in tumor volume of 10% or more was observed in 3 (6%) patients. Previous studies indicated that squamous cell carcinomas regress faster than adenocarcinomas after Gamma Knife treatment or lung SBRT [ 17 , 18 ], but in the present study, 2 of the 3 tumors were adenocarcinomas while one was a squamous cell carcinoma. Rapid decrease of tumor volume during the course of SBRT may be due to apoptosis of the tumor cells [ 19 ].…”

Robotic stereotactic body radiation therapy for elderly medically inoperable early-stage non-small cell lung cancer

“…44 However, a recent prospective study examining the difference in SBRT response between the two histologies showed that although tumor shrinkage was faster for SCC than adenocarcinomas at 2 and 4 months, there was no difference in the mean tumor size at 6 months or in the 3-year LC. 45 Our results are likely biased by the small sample size and the low event rate; caution is therefore exercised in extrapolating any definitive conclusions from the data.…”

Clinical outcomes of stage I and IIA non-small cell lung cancer patients treated with stereotactic body radiotherapy using a real-time tumor-tracking radiotherapy system

“…It is still not commonly agreed whether tumor histology is related to clinical outcomes in NSCLC treated with SBRT. Some studies have reported an absence of statistically significant differences in the survival or recurrence rates of adenocarcinomas and SCC [32, 33]. Matsuo et al analyzed 101 patients with histologically confirmed stage I NSCLC who underwent SBRT [34], and reported that females had a significantly better prognosis than males and that histology was less significant.…”