Thoracic radiation therapy for limited-stage small-cell lung cancer: unanswered questions

eIF3a R803K mutation mediates chemotherapy resistance by inducing cellular senescence in small cell lung cancer

Drug resistance in small cell lung cancer (SCLC) significantly affects the efficacy of chemotherapy treatment. However, due to the lack of tumor tissue samples, especially serial tumor samples during chemotherapy, the mechanism of chemotherapy resistance has not been fully studied. Circulating tumor DNA, which can be obtained in a noninvasive manner, can complement tumor sampling approaches for research in this field. We identified an SCLC patient with acquired drug resistance from 52 SCLC patients for whom follow-up data were available. By comparing somatic mutations in circulating tumor DNA before and after chemotherapy, for the first time, we found that the somatic mutation eIF3A R803K may be related to acquired chemotherapy resistance. Then, the association between the eIF3A R803K mutation and chemotherapy resistance was confirmed by samples from 254 lung cancer patients receiving chemotherapy. We found that the eIF3a R803K mutation weakened the proliferation ability of tumor cells but increased their resistance to chemotherapy. Further studies revealed that the eIF3A R803K mutation promotes cellular senescence. In addition, fisetin showed a synergistic effect with chemotherapy in eIF3A R803K mutant cells. These results suggest that the eIF3A R803K somatic mutation has the potential to predict chemotherapy resistance in SCLC. Moreover, the eIF3A R803K mutation promotes chemotherapy resistance by inducing senescence. Furthermore, a senolytic drug, fisetin, can reverse chemotherapy resistance mediated by the eIF3A R803K mutation.

Multimodality Therapy for Limited-Stage Small-Cell Lung Cancer

Limited-stage small-cell lung cancer (SCLC) occurs in only one third of patients with SCLC, but it is potentially curable. Combined-modality therapy (chemotherapy and radiotherapy) has long been the mainstay of therapy for this condition, but more recent data suggest a role for surgery in early-stage disease. Prophylactic cranial irradiation seems to improve outcomes in patients who have responded to initial therapy. This review addresses the practical aspects of staging and treatment of patients with limited-stage SCLC.

Efficacy of 3D conformal thoracic radiotherapy for extensive-stage small-cell lung cancer: A retrospective study

The aim of the present study was to evaluate the effect of 3-dimensional conformal thoracic radiotherapy (TRT) on extensive-stage small-cell lung cancer (ES-SCLC). A total of 165 patients with ES-SCLC were enrolled in the present study, including 82 patients receiving chemotherapy combined with TRT (the ChT/TRT group) and 83 patients receiving chemotherapy alone (the ChT group). The overall survival (OS) and progression-free survival (PFS) rates were compared between the ChT/TRT and ChT groups, and the prognostic factors for OS rate were identified. It was found that the patients had a median OS time of 15 months, and 2- and 5-year OS rates of 31.5 and 2.4%, respectively. The 2- and 5-year OS rates were 35.3 and 2.4% in the ChT/TRT group, and 14.5 and 2.4% in the ChT group, respectively (P<0.05). The 1- and 2-year PFS rates were 35.4 and 6.0% in the ChT/TRT group, and 20.5 and 6.0% in the ChT group, respectively (P<0.05). The median PFS was 11 months in the 20 patients receiving TRT at 45 Gy/30 fractions twice daily, and 9 months in the 22 patients receiving TRT at 60 Gy/30 fractions daily (P=0.043). Multivariate analysis revealed that receiving ≥4 cycles of chemotherapy (P=0.001) and TRT (P=0.008) were favorable prognostic factors for OS. It was concluded that the addition of TRT improves the OS and PFS rates of patients with ES-SCLC, and TRT administration at 45 Gy/30 fractions twice daily is feasible and tolerable for the treatment of ES-SCLC. Thus, TRT and receiving ≥4 cycles of chemotherapy are independent, favorable prognostic factors for OS in patients with ES-SCLC.

Use of G-CSF during concurrent chemotherapy and thoracic radiotherapy in patients with limited-stage small-cell lung cancer safety data from a phase II trial

There is paucity of data in the literature regarding the safety of combining granulocyte colony stimulating factor (G-CSF) during chemo-radiotherapy (CTRT) in lung cancer patients. The ASCO 2006 recommendations advise against use of CSFs during concomitant mediastinal CTRT. The only randomised study evaluating CSFs in this context showed significant increase in grade 3/4 thrombocytopenia and an excess of pulmonary toxic deaths. In the context of a phase II trial, 38 patients with limited-stage small cell lung cancer were randomised to receive once-daily (66 Gy in 33 fractions) or twice-daily (45 Gy in 30 fractions) radiotherapy. Radiotherapy (RT) was given concurrently with cisplatin and etoposide. G-CSF was given as primary or secondary prophylaxis or as a therapeutic measure during an episode of febrile neutropenia according to local protocols. Common terminology criteria for adverse events (CTCAE) v3.0 was used to record toxicity. Thirteen (34%) of 38 patients received G-CSF concurrently with RT. With a median follow-up of 16.9 months, there were no treatment related deaths reported. Seven (54%) patients experienced grade 3/4 thrombocytopenia and 5 (38%) experienced grade 3/4 anaemia. Thirty-one percent required platelet transfusions. No episodes of bleeding were observed. There were no cases of grade 3/4 acute pneumonitis. These data suggests that with modern three-dimensional (3D) conformal RT, G-CSF administration concurrently with CTRT does not result in the increase risk of pulmonary toxicity, but does increase the risk of thrombocytopenia. Whether the risks of thrombocytopenia are outweighed by the outcome of timely early concurrent CTRT is being evaluated prospectively in the ongoing phase III CONVERT trial (NCT00433563) in which G-CSF is permitted during thoracic irradiation.

[A prospective randomized study of the radiotherapy volume for limited-stage small cell lung cancer: a preliminary report]

BACKGROUND AND OBJECTIVE

Controversies exists with regard to target volumes as far as thoracic radiotherapy (TRT) is concerned in the multimodality treatment for limited-stage small cell lung cancer (LSCLC). The aim of this study is to prospectively compare the local control rate, toxicity profiles, and overall survival (OS) between patients received different target volumes irradiation after induction chemotherapy.

METHODS

LSCLC patients received 2 cycles of etoposide and cisplatin (EP) induction chemotherapy and were randomly assigned to receive TRT to either the post- or pre-chemotherapy tumor extent (GTV-T) as study arm and control arm, CTV-N included the positive nodal drainage area for both arms. One to 2 weeks after induction chemotherapy, 45 Gy/30 Fx/19 d TRT was administered concurrently with the third cycle of EP regimen. After that, additional 3 cycles of EP consolidation were administered. Prophylactic cranial irradiation (PCI) was administered to patients with a complete response.

RESULTS

Thirty-seven and 40 patients were randomly assigned to study arm and control arm. The local recurrence rates were 32.4% and 28.2% respectively (P = 0.80); the isolated nodal failure (INF) rates were 3.0% and 2.6% respectively (P = 0.91); all INF sites were in the ipsilateral supraclavicular fossa. Medastinal N3 disease was the risk factor for INF (P = 0.02, OR = 14.13, 95% CI: 1.47-136.13). During radiotherapy, grade I, II weight loss was observed in 29.4%, 5.9% and 56.4%, 7.7% patients respectively (P = 0.04). Grade 0-I and II-III late pulmonary injury was developed in 97.1%, 2.9% and 86.4%, 15.4% patients respectively (P = 0.07). Median survival time was 22.1 months and 26.9 months respectively. The 1 to 3-year OS were 77.9%, 44.4%, 37.3% and 75.8%, 56.3%, 41.7% respectively (P = 0.79).

CONCLUSIONS

The preliminary results of this study indicate that irradiant the post-chemotherapy tumor extent (GTV-T) and positive nodal drainage area did not decrease local control and overall survival while radiation toxicity was reduced. But the current sample size has not met designed requirements, and further investigation is warranted before final conclusions could be drawn.

Limited-stage small cell lung cancer: current chemoradiotherapy treatment paradigms

In the U.S., the prevalence of small cell lung cancer (SCLC) is declining, probably reflecting the decreasing prevalence of tobacco use. However, a significant number of patients will receive a diagnosis of SCLC, and approximately 40% of patients with SCLC will have limited-stage (LS) disease, which is potentially curable with the combination of chemotherapy and radiation therapy. The standard therapy for LS-SCLC is concurrent chemoradiotherapy, and the 5-year survival rate observed in clinical trials is approximately 25%. The standard chemotherapy remains cisplatin and etoposide, but carboplatin is frequently used in patients who cannot tolerate or have a contraindication to cisplatin. Substantial improvements in survival have been made through improvements in radiation therapy. Concurrent chemoradiotherapy is the preferred therapy for patients who are appropriate candidates. The optimal timing of concurrent chemoradiotherapy is during the first or second cycle, based on data from meta-analyses. The optimal radiation schedule and dose remain topics of debate, but 1.5 Gy twice daily to a total of 45 Gy and 1.8-2.0 Gy daily to a total dose of 60-70 Gy are commonly used treatments. For patients who obtain a near complete or complete response, prophylactic cranial radiation reduces the incidence of brain metastases and improves overall survival. The ongoing Radiation Therapy Oncology Group and Cancer and Leukemia Group B and the European and Canadian phase III trials will investigate different radiation treatment paradigms for patients with LS-SCLC, and completion of these trials is critical.

Accelerated hyperfractionated radiotherapy and concomitant chemotherapy in small cell lung cancer limited-disease. Dose response, feasibility and outcome for patients treated in western Sweden, 1998-2004

Addition of thoracic radiation therapy (TRT) to chemotherapy (CHT) can increase overall survival in patients with small cell lung cancer limited-disease (SCLC-LD). Accelerated fractionation and early concurrent platinum-based CHT, in combination with prophylactic cranial irradiation, represent up-front treatment for this group of patients. Optimised and tailored local and systemic treatment is important. These concepts were applied when a new regional treatment programme was designed at Sahlgrenska University Hospital in 1997. The planned treatment consisted of six courses of CHT (carboplatin/etoposide) + TRT +/- prophylactic cranial irradiation (PCI). Standard TRT was prescribed at 1.5 Gy BID to a total of 60 Gy during 4 weeks, starting concomitantly with the second or third course of CHT. However, patients with large tumour burdens, poor general condition and/or poor lung function received 45 Gy, 1.5 Gy BID, during 3 weeks. PCI in 15 fractions to a total dose of 30 Gy was administered to all patients with complete remission (CR) and "good" partial remission (PR) at response evaluation. Eighty consecutive patients were treated between January 1998 and December 2004. Forty-six patients were given 60 Gy and 34 patients 45 Gy. Acute toxicity occurred as esophagitis grade III (RTOG/EORTC) in 16% and as pneumonitis grade I-II in 10%. There were no differences in toxicity between the two groups. Three- and five-year overall survival was 25% and 16%, respectively. Medica survival was 20.8 months with no significant difference between the two groups. In conclusion, TRT with a total dose of 60 to 45 Gy is feasible with comparable toxicity and no difference in local control or survival. Distant metastasis is the main cause of death in this disease; the future challenge is thus further improvement of the systemic therapy combines with optimised local TRT.

Limited-stage small-cell lung cancer: the current status of combined-modality therapy

Limited-stage (LS) small-cell lung cancer (SCLC) remains a therapeutic challenge to medical and radiation oncologists. The treatment of LS-SCLC has evolved significantly over the last two decades with combined-modality therapy now the standard of care. The addition of thoracic radiotherapy (TRT) to standard chemotherapy has led to improvements in long-term survival in this population. However, many questions remain about the optimal way to deliver chemoradiotherapy. In a landmark trial, twice-daily TRT to a dose of 45 Gy increased 5-year survival by 10% compared with once-daily TRT administered to the same dose. This suggests that more intensive TRT regimens may lead to further survival gains, assuming they can be delivered safely in this setting. Strategies currently under investigation include higher total daily doses delivered once daily or novel concurrent boost techniques allowing more intensive treatments over shorter periods of time. Several trials and meta-analyses have evaluated the timing of TRT with chemotherapy, with the weight of evidence suggesting that early and concurrent TRT with chemotherapy is optimal. Novel cytotoxic chemotherapy combinations have failed thus far to provide an advantage over standard etoposide-cisplatin combinations. Prophylactic cranial irradiation in near or complete responders to induction chemoradiotherapy has also been shown to improve long-term survival rates. LS-SCLC has been a model cancer in terms of the potential benefit of combined chemoradiotherapy strategies in improving patient outcomes.