As MRI is more sensitive, do you think patients should have MRI liver to look for metastases if CT is clear?
This is a great question as clearly liver MRI has a greater sensitivity for detecting metastatic disease than other modalities. Ultimately, the decision to perform another staging investigation depends on the balance between cost, available resources and inconvenience to the patient versus any potential benefit arising from up-staging. This consideration needs to be risk-assessed for each individual patient. For healthcare systems that can afford it, the trend is for liver MRI at initial staging in those patients that are high risk for liver metastases and are going to be suitable candidates for radical treatment for stage 4 disease. Therefore patient’s wishes, fitness and tumour characteristics seen on the pelvic MRI such as extra-mural venous invasion and advanced T-stage will inform this decision. In our unit, we will not routinely perform liver MRI unless the CT has shown an abnormality. Occasionally in a young fit patient with an extremely high risk primary tumour, we have gone ahead and arranged both pelvic and liver MRI at the outset. In the age of total neoadjuvant therapy for high risk cancers, it is useful to know what the baseline liver imaging is like, as the first treatment will be chemotherapy and most liver metastases will re-appear at some point in the future even if they are not seen after neoadjuvant therapy. Bear in mind that a liver MRI is a prolonged and unpleasant investigation for the patient.
A CT scan is still the most appropriate screening investigation in terms of cost, convenience and patient acceptance. In addition it provides information regarding any extra-hepatic spread which will dictate subsequent therapy.
What advantages do you see in the simultaneous resection of metastases and the primary tumour.
In our network, the vast majority of primary rectal cancers are resected prior to any liver surgery, either with or without neoadjuvant therapy. However, high-risk metastatic liver disease (determined by size, number and location) will occasionally require a liver-first approach. The advantages of a simultaneous approach are that the patient can have all their disease resected under a single anaesthetic and there is no need to re-enter a potentially hostile abdomen. Clearly if the patient suffers a serious complication of their first operation, then there will be a delay in treatment for the remainder of their disease. However, performing major liver surgery, with all its associated risks of reduced hepatic function in the recovery period, makes simultaneous resections risky if there are any complications from the rectal resection. Patients with liver failure do not deal with sepsis well. As most rectal resections are inherently risky by definition, simultaneous surgery of primary and secondary tumours is usually reserved for colonic resections in fit patients with liver metastases that are straightforward to remove and leave plenty of functional liver to cope with any potential complications. The use of novel imaging to predict post-operative hepatic function will help to guide these decisions and potentially improve outcomes.