The PulMiCC Trial Provides Control Data for Colorectal Lung Metastases Amenable to Local Treatments
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LETTER TO THE EDITOR
The PulMiCC Trial Provides Control Data for Colorectal Lung Metastases Amenable to Local Treatments Norman R. Williams1 • Misˇel Milosˇevic´2 • Tom Treasure3
•
Fergus Macbeth4
Received: 14 September 2020 / Accepted: 4 November 2020 Springer Science+Business Media, LLC, part of Springer Nature and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2020
Dear Editor, We appreciate Zhong et al. referring to PulMICC, the Pulmonary Metastasectomy in Colorectal Cancer randomised controlled trial (RCT) in their paper published online on 18 August 2020 [1]. But it was misleading to write that PulMICC ‘‘had to be stopped’’ and to not indicate its findings. We wish to correct that misconception and bring to the attention of the authors and the Journal’s readers the results of the trial published this year [2]. The PulMiCC Trial was closed by the investigators for analysis and publication. This was after discussion and with the approval of the Independent Data Monitoring Committee. We have now published results for all 93 randomised patients. The median survival after lung metastasectomy was 3.5 years compared with 3.8 in the control group (Fig. 1). At four years, survival in the metastasectomy arm 44% (95% CI 29–61%) and in the control arm, it was 47% (95% CI: 32–63%). It is true that the randomisation target, calculated to tests for non-inferiority, was more than three times the number recruited but as Cox writes, the power calculation is ‘‘quite irrelevant in the actual analysis of data’’.
& Tom Treasure [email protected] 1
Surgical and Interventional Trials Unit (SITU), University College, London, UK
2
Thoracic Surgery Clinic, Institute for Lung Diseases of Vojvodina, Sremska Kamenica, Serbia
3
Clinical Operational Research Unit (CORU), University College, London, UK
4
Centre for Trials Research, Cardiff University, Cardiff, UK
Survival in the metastasectomy arm was similar to that in the many uncontrolled reports of local treatment for colorectal metastases to the lung, but the five-year survival in the control group was much higher than the near-zero assumed in the Society of Thoracic Surgeons Expert Consensus Document [3] and the 6.9% referred to by Zhong et al. PulMiCC control survival is in agreement with only two other randomised controlled trials of local treatment of metastases of which we are aware, SABR-COMET and CLOCC. Survival among patients, randomised to not have ablation or metastasectomy in CLOCC and PulMiCC taken together (N=106) had a weighted combined estimate of 30 per cent (95% confidence intervals 21–40%) derived using a complementary log–log scale which is very different from previous estimates (P \ 0.001) [4]. The authors frequently refer to the ‘‘favourable survival’’ from surgical or RFA intervention but, in the absence of control data, survival cannot be attributed to the effect of the interventions, rather than to case selection alone. Progression-free survival is a self-fulfilling outcome because the only evident disease has be
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