Surgery for colorectal lung metastases
I see a number of patients with treated colorectal cancer, who unfortunately develop deposits in the lung. The main question is on the appropriateness and suitability of lung surgery to remove them.
This is a very interesting question and field, as opinions amongst specialists are widely divided (distinct lack of equipoise) as there is little high quality evidence in the literature to support either argument (surgery or no surgery).
A randomised clinical trial was conducted (PulMiCC) to address this precise question in the UK. However, there were a number of twists in the plot that would subvert the trial conduct and hence validity of the conclusions.
The first was the assumption that the patients would come readily from thoracic surgeons willing to offer the trial (that was correct and we did). The flaw in the assumption however was that thoracic surgeons in the UK controlled the flow of patients - this was very clearly not the case. The flow of patients came from colorectal cancer MDT, and boy were we wrong that they had equipoise on the question and would support the trial. Some were so convinced that surgery worked, they diverted the referral flow of patients to other thoracic surgery sites that were not participating in PulMiCC. The trial was not a thoracic surgical trial, it was a colorectal MDT trial. Whilst there many additional possible reasons (original trials unit closing down, treatment pathways changing to include ablation etc…) I believe lack of colorectal MDT support was the main reason the trial could not be completed.
At the end, PulMiCC reported after randomizing 65 participants [and later re-reported on 93 randomized participants] out of an initial planned 300, leaving it well short of the mark to establish an answer (of no effect) with any level of certainty. What then evolves is the trial management group not accepting the uncertainty, but continuing to take a position contrary to the data; that surgery is unlikely to have any meaningful influence on survival despite reporting initial estimates of improved survival with surgery between 8 to 31% [1] later revised to an improvement of between 7% to 13%. [2]
Either way, the final conclusion (in my opinion) is simply - uncertain. I prefer to take the more modest unadjusted improvement of 7% to look at how uncertain the conclusion was [0.93 (95% CI: 0.56–1.56)] which implies range from a 46% improvement in survival to a 56% increase in death.[2]
To me, the most striking outcome of PulMiCC was clinicians in the UK (because of lack of equipoise) were unwilling to support efforts to address an important clinical question, and those that conducted and supported the trial (because of lack of equipoise) were unwilling to conclude in accordance with reported outcome data (in that that we simply don’t know).
So, as of today - your opinion as a patient whether you wish to have surgery (or not) is as valid as any expert in this field.
Eric Lim
[1] Treasure T, Farewell V, Macbeth F, Monson K, Williams NR, Brew-Graves C, Lees B, Grigg O, Fallowfield L and PulMi CCTG. Pulmonary Metastasectomy versus Continued Active Monitoring in Colorectal Cancer (PulMiCC): a multicentre randomised clinical trial. Trials. 2019;20:718.
[2] Milosevic M, Edwards J, Tsang D, Dunning J, Shackcloth M, Batchelor T, Coonar A, Hasan J, Davidson B, Marchbank A, Grumett S, Williams NR, Macbeth F, Farewell V and Treasure T. Pulmonary Metastasectomy in Colorectal Cancer: updated analysis of 93 randomized patients - control survival is much better than previously assumed. Colorectal Dis. 2020.