Involved field radiotherapy for locally advanced non-small cell lung cancer: isolated mediastinal nodal relapse

IMRT in the treatment of locally advanced or inoperable NSCLC in the pre-durvalumab era: clinical outcomes and pattern of relapses, experience from the Oscar Lambret Center

Background

Intensity-modulated conformal radiotherapy (IMRT) has become the technique of choice for the treatment of locally advanced or inoperable non-small cell lung cancer (NSCLC). Nevertheless, this technique presents dosimetric uncertainties, particularly in treating moving targets such as pulmonary neoplasms. Moreover, it theoretically increases the risk of isolated nodal failure (INF) due to reduced incidental irradiation.

Objective

The objective of this study was to evaluate the efficacy and safety of IMRT in patients with inoperable NSCLC and to describe the pattern of relapses.

Methods

Patients with locally advanced NSCLC treated with radiotherapy and chemotherapy between 2015 and 2018 at the Oscar Lambret Center were retrospectively included in the study. Overall and progression-free survival were estimated using the Kaplan-Meier method. The cumulative incidence of the different components of relapse was estimated using the Kalbfleisch and Prentice method. Prognostic factors for relapse/death were investigated using the Cox model. A comparison with literature data was performed using a one-sample log-rank test.

Results

Seventy patients were included, and 65 patients (93%) had stage III disease. All the patients received chemotherapy, most frequently with cisplatin and navelbine. The dose received was 66 Gy administered in 33 fractions. The median follow-up and survival were 49.1 and 39.1 months, respectively. A total of 35 deaths and 43 relapses, including 29 with metastatic components, were reported. The overall survival rates at 1 and 2 years were 80.2% (95% confidence interval 68.3%-88.0%) and 67.2% (95% confidence interval 54.2%-77.3%), respectively. Locoregional relapse was observed in 14 patients, including two INF, one of which was located in the lymph node area adjacent to the clinical target volume. Median relapse-free survival was 15.2 months. No variable was statistically associated with the risk of relapse/death in multivariate analysis. Seven patients (10%) experienced grade 3 or higher toxicity.

Conclusion

The use of IMRT for locally advanced or inoperable NSCLC led to favorable long-term clinical outcomes. The rate of locoregional relapse, particularly isolated lymph node failure, was low and comparable with that of the three-dimensional radiotherapy series, as was the rate of early and late toxicities.

[Lung cancer and elective nodal irradiation: A solved issue?]

Lung cancer treatment is a heavy workload for radiation oncologist and that field showed many evolutions over the last two decades. The issue about target volume was raised when treatment delivery became more precise with the development of three-dimensional conformal radiotherapy. Initially based upon surgical series, numerous retrospective and prospective studies aimed to evaluate the risk of elective nodal failure of involved-field radiotherapy compared to standard large field elective nodal irradiation. In every setting, locally advanced non-small cell lung cancer, localized non-small cell lung cancer, localized small cell lung cancer, exclusive chemoradiation or postoperative radiotherapy, most of the studies showed no significant difference between involved-field radiotherapy or elective nodal irradiation with elective nodal failure rate under 5% at 2 years, provided staging had been done with modern imaging and diagnostic techniques (positron emission tomography scan, endoscopy, etc.). Moreover, if reducing irradiated volumes are safe regarding recurrences, involved-field radiotherapy allowed dose escalation while reducing acute and late oesophageal, cardiac and pulmonary toxicities. Consequently, major clinical trials involving radiotherapy initiated in the last two decades and international clinical guidelines recommended omission of elective nodal irradiation in favour of in-field radiotherapy.

MicroRNA-198 inhibition of HGF/c-MET signaling pathway overcomes resistance to radiotherapy and induces apoptosis in human non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is the most common cause of death from cancer worldwide. MicroRNAs (miRNAs) are a group of important regulators in NSCLC, including miR-198. However, the underlying molecular mechanisms of miR-198 involvement in intrinsic resistance to radiotherapy in NSCLC remain to be elucidated. In this study, to investigate the clinical significance of miR-198 in NSCLC in relation to the response to radiotherapy, we determined the expression patterns of miR-198 between responders and nonresponders after 2 months of radiotherapy and found that decreased expressions of miR-198 were associated with radiotherapy resistance. In addition, we altered the endogenous miR-198 using mimics or inhibitors to examine the effects of miR-198 on 4-Gy-irradiated A549 and SPCA-1 cells in vitro. Upregulating miR-198 was shown to inhibit cell proliferation, migration, and invasion and induce apoptosis. MiR-198 inhibition produced a reciprocal result. PHA665752, a selective small-molecule c-Met inhibitor, potently inhibited hepatocyte growth factor (HGF)-stimulated and constitutive c-Met phosphorylation and rescued 4-Gy-irradiated A549 and SPCA-1 cells from miR-198 inhibition. Most importantly, we established tumor xenografts of 4-Gy-irradiated A549 and SPCA-1 cells in nude mice and found that miR-198 could suppress tumor formation. Hence, our data delineates the molecular pathway by which miR-198 inhibits NSCLC cellular proliferation and induces apoptosis following radiotherapy, providing a novel target aimed at improving the radiotherapeutic response in NSCLC.

Overlooking evolution: a systematic analysis of cancer relapse and therapeutic resistance research

Cancer therapy selects for cancer cells resistant to treatment, a process that is fundamentally evolutionary. To what extent, however, is the evolutionary perspective employed in research on therapeutic resistance and relapse? We analyzed 6,228 papers on therapeutic resistance and/or relapse in cancers and found that the use of evolution terms in abstracts has remained at about 1% since the 1980s. However, detailed coding of 22 recent papers revealed a higher proportion of papers using evolutionary methods or evolutionary theory, although this number is still less than 10%. Despite the fact that relapse and therapeutic resistance is essentially an evolutionary process, it appears that this framework has not permeated research. This represents an unrealized opportunity for advances in research on therapeutic resistance.