[MUSIC PLAYING]

SEAN CLEARY: Colorectal cancer is obviously one of the most common cancers in North America. It's about the third most common fatal cancer. Unfortunately, about a 1/3 of patients with colon cancer will develop spread to the liver at some point in time of their diagnosis. It's very important that we make sure that we differentiate between benign liver lesions, which many patients have, and actual metastasis. So that's why the workup is important.

Most patients can be diagnosed just on CT scan or MRI alone. Typical view of colorectal cancer is this is something that affected people in their 60s and 70s. We're seeing much more cases of colorectal cancer in younger populations, patients in their mid-20s and early 30s. But I don't think we have very firm understanding of why we're seeing advanced colorectal cancer in younger populations.

There are certainly some trends that we're observing just in terms of people's size, in terms of as the population obesity rates rise. We certainly know that some of the younger patients with colon cancer can have very aggressive disease. And so therefore, we need to be very aggressive in return.

We've looked at neoadjuvant chemotherapy prior to liver resection for metastatic colorectal cancer and a couple of randomized trials. We have the EPOCH 1 study, which compared FOLFOX to placebo prior to liver resection. That showed a benefit in disease-free and overall survival in patients that received chemotherapy.

The results were not as dramatic as we were expecting. But I think that certainly did, at least, reinforce that there was a positive trend. The follow-up study to that used an agent called an EGFR inhibitor, Cetuximab, added to the chemotherapy. And unfortunately, we found that the addition of an EGFR inhibitor to chemotherapy before liver surgery had a detrimental effect.

It speaks to, really, why we need to take a very personalized approach to patients in these situations. And we need to evaluate resectability early in the disease course. Because it can have impact on the type of chemotherapy agents that we select, but also the duration of chemotherapy that we want to do before liver surgery.

That's where I think an in-depth knowledge of liver surgery is important. Because while in the past, we used to count lesions, or look at their number and their size, or we used to think that patients had to have spots on one side of their liver and not the other, all of those rules have gone out the window now. Now we can offer surgery to patients as long as we can remove all of the lesions that we see and have an adequate liver volume after the operation for the patient to survive.

So we need about approximately 30% of their original liver size to be left at the end of the operation to ensure that the patient has enough liver to get safely through the post-operative period. If that's not enough, if we see patients where they don't have enough anticipated liver volume, we can modulate that. We can grow that area of the liver before the operation to make the operation safer.

The ability to grow the liver before the operation has been a phenomenal advance. It's allowed us to offer surgery to so many more patients. The most common technique that we have is what we call portal vein embolization, where we actually block off the portal vein to the areas that have the cancer in it.

So the portal vein carries about 2/3 of the blood supply to the liver. If we block off that vein to the affected side of the liver, we-- that shunts blood to the good side of the liver and encourages that part of the liver to grow. And so we can see that area of the liver increased by 50%, even double, given adequate time of about six weeks for that to grow after that procedure.

One of the things about liver surgery is that there's a very strong volume to outcome relationship. So we know that the risk of post-operative complications, and the risk of adverse outcomes, and the chances of survival after liver surgery are directly correlated to the number of procedures that an institution does.

I think at Mayo Clinic, we're really able to offer not only very safe but also very aggressive liver surgery. We not only have the standard of care approaches, but we also have investigative approaches in terms of not only offering surgery to more patients but improving their outcomes after surgery.

[MUSIC PLAYING]