Stereotactic Body Radiotherapy Yields Similar Outcomes in Patients With Biopsy-Proven vs Radiographically Diagnosed Early-Stage NSCLC
In patients with early-stage non–small cell lung cancer (NSCLC) treated with stereotactic body radiotherapy, outcomes were similar between patients with biopsy-proven lesions and those with radiographically diagnosed disease, according to a study by Fischer-Valuck et al in Tumori Journal. Thus, the investigators concluded, stereotactic body radiotherapy may be a practical treatment option for patients who are not eligible for biopsy.
Study Background
NSCLC accounts for approximately 85% of all diagnosed lung cancer cases in the United States. Among patients diagnosed with NSCLC, approximately 25% have early-stage disease. The standard of care for early-stage NSCLC remains surgical resection. However, many patients with early-stage disease have multiple comorbidities that preclude surgery, including advanced chronic obstructive pulmonary disease and cardiovascular disease.
For this patient population, radiotherapy is an alternative treatment; however, outcomes associated with conventional external-beam radiation therapy have been disappointing. Therefore, researchers have been studying the use of stereotactic body radiotherapy, which in early trials has yielded local control rates comparable to those seen with lobectomy.
In many patients, pathologic confirmation of NSCLC is required before patients are offered stereotactic body radiotherapy as a treatment option. This is a potential obstacle, since many of these patients are unable to undergo biopsy procedures or have had failed biopsy attempts.
With that in mind, Fischer-Valuck and colleagues conducted a study to determine whether patients without histologic confirmation of NSCLC will achieve similar outcomes when compared with patients who have biopsy-proven lesions.
Population and Methods
The study included 88 patients with either biopsy-proven or radiographically diagnosed stage I NSCLC. Of those with tissue-diagnosed disease, more than 90% were deemed medically inoperable, and the others opted for radiation therapy as an alternative to surgery. The mean age was 72 years in the biopsy-proven group and 75 years in the radiographically diagnosed group (P = .90).
All patients received radiation therapy with either 10- or 12-Gy total fractions (two immediately sequential 5-Gy or 6-Gy doses after position verification), reaching a dose of 48, 50, or 60 Gy. The target was determined by creating a positron-emission tomography (PET) gross tumor volume based on planning PET/computed tomography (CT) scans and a CT gross tumor volume based on CT simulation.
No Statistical Difference in Survival
The cumulative local progression-free rate after 3 years was 93.1% (95% confidence interval [CI] = 85.2%–97.6%) for the biopsy-proven group and 94.1% (95% CI = 73.2%–97.6%) for the radiographically diagnosed group (P = .98). The 3-year regional lymph node metastasis–free and distant metastasis–free rates for patients with biopsy-proven disease were 92.5% (95% CI = 83.2%–96.7%) and 87.4% (95% CI = 77.5%–93.6%), respectively.
The overall 3-year survival rate was 59.9% (95% CI = 44.8%–68.2%) for the biopsy-proven group vs 58.9% (95% CI = 40.1%–77.8%) for the radiographically diagnosed group. Again, there was no statistical difference between the two groups (P = .46).
Regarding toxicity, nine patients (14%) in the biopsy-proven group and four patients (17%) in the radiographically diagnosed group developed stereotactic body radiation therapy–induced adverse events. Acute chest wall pain was reported in six patients (9%) in the biopsy-proven group and two patients (9%) in the radiographically diagnosed group.
Closing Thoughts
The researchers concluded that the data comparing biopsy-proven lesions and unbiopsied nodules were nearly identical, with no statistically significant difference in any category. Of even greater significance, there was no difference in overall survival between the two groups. In addition, toxicity was relatively low in both groups.
The researchers also noted that, unlike techniques used in previous studies of stereotactic body radiation therapy in early-stage NSCLC, their diagnostic approach was stricter. All patients required both serial CT imaging and an 18F-fluorodeoxyglucose (FDG)-avid nodule confirmed via PET prior to diagnosis.
“While our institution still strongly recommends biopsy for the diagnosis of lung cancer, we found that patient selection including rigorous radiographic workup including both CT and FDG-PET can help identify a population of patients who are most likely to benefit from stereotactic body radiation therapy without biopsy,” the investigators concluded.
Benjamin W. Fischer-Valuck, MD, Department of Radiation Oncology, Washington University School of Medicine, St. Louis, is the corresponding author of this article in Tumori Journal.
The authors reported no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
