Safety of G-CSF with concurrent chemo-radiotherapy in limited-stage small cell lung cancer - Secondary analysis of the randomised phase 3 CONVERT trial

OBJECTIVES

The use of granulocyte colony-stimulating factors (G-CSF) during concurrent chemo-radiotherapy (cCTRT) for small cell lung cancer is not recommended by the American Society of Clinical Oncology due to safety concerns. This secondary analysis explored the safety and the role of prophylactic G-CSF (proG-CSF) in the delivery of cCTRT.

MATERIAL AND METHODS

Secondary analysis of 487 patients treated as per protocol on the phase 3 CONVERT trial which randomized patients between once-daily RT or twice-daily.

RESULTS

180 of 487 eligible patients (37 %) received proG-CSF, 60 (33 %) as primary prophylaxis and 120 (67 %) as secondary prophylaxis following myelotoxic events. The regimen incidence of febrile neutropenia (FN) was 22 %. Its incidence in the proG-CSF group reduced significantly when proG-CSF was administered (22 % vs 10 %; OR 0.4; 95 %CI 0.2-0.7; p = 0.002). The rate of blood transfusion was higher in the proG-CSF group (51 % vs 31 %; OR 2.4; 95 %CI 1.6-3.5; p < 0.001). The incidence of severe thrombocytopenia was also higher is this group (28 % vs 15 %; OR 2.2; 95 %CI 1.4-3.5; p = 0.001). But this was significantly higher in those on secondary vs primary prophylaxis (34 % vs 15 %; OR 2.9; 95 %CI 1.3-7.4 p = 0.009) No differences observed in RT-related toxicity, treatment-related mortality or any survival outcomes. The optimal dose intensity (85 % or higher) of cisplatin was achieved in more patients within the proG-CSF group (75 % vs 67 %; OR 1.5; 95 %CI 0.9-2.3; p = 0.056).

CONCLUSION

There was no evidence that G-CSF directly caused myelotoxicity, instead most patients started G-CSF due to higher myelotoxicity risk. G-CSF maintained the planned dose intensity and there was no detrimental effect on survival. G-CSF may be considered as a supportive measure in this setting.

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.