Phase I study of hypofractionated dose-escalated thoracic radiotherapy for limited-stage small-cell lung cancer

Is There a Role for Hypofractionated Thoracic Radiation Therapy in Limited-Stage Small Cell Lung Cancer? A Propensity Score Matched Analysis

Purpose

Various radiation schedules are used in concurrent chemoradiation therapy for limited-stage small cell lung cancer (LS-SCLC). Since there is currently no randomized evidence comparing hypofractionated radiation therapy (HFRT) and conventionally fractionated radiation therapy (CFRT), the aim of this study was to compare overall survival (OS), progression-free survival (PFS), and toxicity of HFRT and CFRT in LS-SCLC.

Methods and Materials

Patients with LS-SCLC treated between 2000 and 2013 with HFRT (40 Gy/15 fractions, 45 Gy/15 fractions, 45 Gy/20 fractions) or CFRT (60 Gy/30 or 66 Gy/33 fractions) were included. Propensity scores were generated using a multivariable logistic regression model. Patients were matched on a 1:1 ratio with a caliper distance of 0.20. OS and PFS were estimated by the Kaplan-Meier method and compared using log-rank tests. As a sensitivity analysis, univariable and multivariable Cox regression was performed including all patients without matching. Logistic regression was performed to identify predictors of pulmonary and esophageal adverse events.

Results

In the overall group of 117 patients, there were significant baseline differences between the HFRT and CFRT cohorts. Patients who received CFRT were older, more often smoked concurrently with treatment, had higher Eastern Cooperative Oncology Group performance status, different T and N stage patterns, and more commonly received concurrent chemoradiation therapy and prophylactic cranial irradiation. After propensity score matching for these differences, 72 patients were included, 36 in the HFRT and CFRT cohorts, respectively. There was no difference in OS (P = .724), PFS (P = .862), or any pulmonary (P = .350) or esophageal (P = .097) adverse events between cohorts. Skin adverse events were significantly higher for CFRT (41.7%) compared with HFRT (16.7%, P = .020). Multivariable Cox regression also revealed no differences in OS (P = .886) or PFS (P = .717) between all HFRT and CFRT patients, without matching. No grade 5 adverse events were observed.

Conclusions

In LS-SCLC patients, HFRT was associated with comparable survival and toxicity outcomes and may be considered as an alternative to CFRT, should its efficacy be confirmed in prospective studies.

The Current Role of Radiotherapy in the Treatment of Small Cell Lung Cancer

Radiotherapy has been shown to play a key role in the management of small cell lung cancer. There are well-established data in the literature for the use of concurrent chemoradiotherapy for stage I-III disease, although key questions remain over the timing of radiation, the optimal dose/fractionation and particularly once versus twice daily treatment, the use of elective nodal irradiation and drug combinations. Data for the use of thoracic radiation in stage IV disease, after chemotherapy, have recently become available and are leading to a change in practice. Prophylactic cranial irradiation has been shown to be of use in both stage I-III and stage IV disease, although uncertainties surround its use in the elderly population and the use of brain imaging before treatment. This overview will address the current available evidence and focus on areas for future research.

Phase 2 study of accelerated hypofractionated thoracic radiation therapy and concurrent chemotherapy in patients with limited-stage small-cell lung cancer

PURPOSE

To prospectively investigate the efficacy and toxicity of accelerated hypofractionated thoracic radiation therapy (HypoTRT) combined with concurrent chemotherapy in the treatment of limited-stage small-cell lung cancer (LS-SCLC), with the hypothesis that both high radiation dose and short radiation time are important in this setting.

METHODS AND MATERIALS

Patients with previously untreated LS-SCLC, Eastern Cooperative Oncology Group performance status of 0 to 2, and adequate organ function were eligible. HypoTRT of 55 Gy at 2.5 Gy per fraction over 30 days was given on the first day of the second or third cycle of chemotherapy. An etoposide/cisplatin regimen was given to 4 to 6 cycles. Patients who had a good response to initial treatment were offered prophylactic cranial irradiation. The primary endpoint was the 2-year progression-free survival rate.

RESULTS

Fifty-nine patients were enrolled from July 2007 through February 2012 (median age, 58 years; 86% male). The 2-year progression-free survival rate was 49.0% (95% confidence interval [CI] 35.3%-62.7%). Median survival time was 28.5 months (95% CI 9.0-48.0 months); the 2-year overall survival rate was 58.2% (95% CI 44.5%-71.9%). The 2-year local control rate was 76.4% (95% CI 63.7%-89.1%). The severe hematologic toxicities (grade 3 or 4) were leukopenia (32%), neutropenia (25%), and thrombocytopenia (15%). Acute esophagitis and pneumonitis of grade ≥3 occurred in 25% and 10% of the patients, respectively. Thirty-eight patients (64%) received prophylactic cranial irradiation.

CONCLUSION

Our study showed that HypoTRT of 55 Gy at 2.5 Gy per fraction daily concurrently with etoposide/cisplatin chemotherapy has favorable survival and acceptable toxicity. This radiation schedule deserves further investigation in LS-SCLC.

A systematic methodology review of phase I radiation dose escalation trials

BACKGROUND AND PURPOSE

The purpose of this review is to evaluate the methodology used in published phase I radiotherapy (RT) dose escalation trials. A specific emphasis was placed on the frequency of reporting late complications as endpoint.

MATERIALS AND METHODS

We performed a systematic literature review using a predefined search strategy to identify all phase I trials reporting on external radiotherapy dose escalation in cancer patients.

RESULTS

Fifty-three trials (phase I: n = 36, phase I-II: n = 17) fulfilled the inclusion criteria. Of these, 20 used a modified Fibonacci design for the RT dose escalation, but 32 did not specify a design. Late toxicity was variously defined as > 3 months (n = 43) or > 6 months (n = 3) after RT, or not defined (n = 7). In only nine studies the maximum tolerated dose (MTD) was related to late toxicity, while only half the studies reported the minimum follow-up period for dose escalation (n = 26).

CONCLUSION

In phase I RT trials, late complications are often not taken into account and there is currently no consensus on the methodology used for radiation dose escalation studies. We therefore propose a decision-tree algorithm which depends on the endpoint selected and whether a validated early surrogate endpoint is available, in order to choose the most appropriate study design.

Proton therapy in lung cancer: clinical outcomes and technical issues. A systematic review

BACKGROUND AND PURPOSE

To determine whether, according to the currently available literature, proton therapy (PT) has a role in the treatment of non-small-cell lung cancer (NSCLC), to assess its safety and efficacy and to evaluate the main technical issues specifically related to this treatment technique.

MATERIALS AND METHODS

During March 2007, two independent researchers conducted a systematic review of the current data on the treatment of NSCLC with PT.

RESULTS

In total, 113 reports were retrieved, 17 of which were included in the analysis. There were no prospective trials (randomized or non-randomized). Nine uncontrolled single-arm studies were available from three PT centers, providing clinical outcomes for 214 patients in total. These reports were mainly related to stage I-II tumors, with results comparable to those obtained with surgery, without significant toxicity. In addition, two papers were found that compared photon and proton dose distributions, which showed a potential for dose escalation and/or a sparing of the organ at risk with PT. Finally, six studies analyzed dosimetric and technical issues related with PT, mainly underlining the difficulties in designing dose distributions that are representative of the dose actually delivered during treatment.

CONCLUSIONS

Although from a physical point of view PT is a good option for the treatment of NSCLC, limited data are available on its application in the clinical practice. Furthermore, the application of PT to lung cancer does present technical challenges. Because of the small number of institutions involved in the treatment of this disease, number of patients, and methodological weaknesses of the trials it is therefore not possible to draw definitive conclusions about the superiority of PT with respect to the photon techniques currently available for the treatment of NSCLC.