A 51-year-old man presented with anemia and a colonoscopy that revealed cecal cancer. He underwent a right hemicolectomy and pathology confirmed the tumor to be T3N1Mx. He was then referred to a medical oncologist for adjuvant therapy, where staging CT identified three hepatic metastases: one located centrally, one near the right portal pedicle and one adjacent to the gall bladder. Uninvolved segments I, II and III appear notably small in size, and volumetric study confirms only an estimated 16 percent postresection hepatic reserve. The patient underwent PVE with concomitant preoperative FOLFOX/bevacizumab for four cycles. Scans indicated right-sided tumor shrinkage from chemotherapy and desired left lobe hypertrophy (volume 16 to 27 percent). He then underwent successful extended right hepatectomy followed by eight cycles of postoperative FOLFOX/bevacizumab.
Case Discussion:
DR CHOTI: This was a 51-year-old man who presented with anemia. Further workup, including a colonoscopy, revealed cecal cancer. He subsequently underwent a right hemicolectomy and pathology confirmed a T3N1 tumor. He was referred to a medical oncologist for adjuvant therapy, and the medical oncologist ordered a CT scan that identified hepatic metastases, indicating that the patient’s disease had been staged inadequately before surgery. This patient was initially thought to have Stage IV disease, but the metastases were not found until after surgery. He had three metastases: a large central metastasis, a tumor in the right liver near the right portal pedicle and a third one near the right side of the gallbladder. His disease was assessed as potentially resectable. The left lateral sector of the liver, the so-called segments II, and III, was not involved but the liver remnant would be too small according to volumetrics, which showed only 16 percent of the liver would remain.
Even in the healthiest livers, the data suggest that you need at least a 20 percent remnant. The radiologist can calculate the volume of the remnant liver by dividing the total liver volume by the measured remnant volume. Instead of measuring liver volume, we estimate the total liver volume based on height and weight.
If the liver is resectable, but not safe to resect because the remnant liver would be too small, we use a procedure called PVE, a technique that involves injecting material into the right portal vein, almost like chemoembolization. The injected gel clogs off the right portal vein, causing the right half of the liver to be stressed and to partially shrivel, and the left half of the liver — the part that wasn’t injected — to start growing to compensate for the damaged right half of the liver. We normally rescan the liver approximately four to five weeks after PVE and then recalculate the volume. If the liver is growing sufficiently, we proceed with the surgery. If it is not sufficient in size, we recalculate the volume a month later.
If you plan to administer neoadjuvant chemotherapy, consider providing a few cycles of chemotherapy to evaluate response while you wait for the liver to hypertrophy. This is how we proceeded with this patient. The chemotherapy does two things: it keeps the tumor in check, but more importantly, the patient is chemotherapy-naïve — so even if the patient initially had resectable disease, we would want to treat with neoadjuvant chemotherapy. Studies have shown that liver regeneration in not inhibited by chemotherapy.
Four cycles of FOLFOX/bevacizumab were initiated, and then the patient was rescanned. The tumor size decreased, and the proposed remnant liver grew from 16 percent to 27 percent — almost doubled in size — which was quite dramatic. Subsequently, the patient underwent successful chemotherapy and received adjuvant chemotherapy with another six to eight cycles of FOLFOX/bevacizumab.
Good-quality cross-sectional imaging of the liver, in addition to the abdomen and chest in some cases, are required to evaluate the number of tumors and their size and location, relative to the structures within the liver. The most common cross-sectional imaging used is CT. The quality is excellent and it is the least expensive option. It must be contrast-enhanced CT — high-quality cross-sectional imaging, likely CT scanning with contrast, is one of the mainstays of imaging before considering surgical therapy on the liver. One could use a contrast-enhanced MRI in some cases — it depends on the institution. I don’t think MRI adds much more, but in some centers it’s helpful. In some cases — with chemoembolization or PVE — MRI is used because the contrast material that’s injected for these intra-arterial or intravascular procedures can make the CT result in poorer quality. Therefore, occasionally we’ll perform MRI.
In addition, we generally recommend a PET scan in patients before undergoing surgical therapy of the liver, because a PET scan is more sensitive at detecting metastatic disease both within and outside the liver, in peritoneal implants, in lymph nodes and throughout the body. In contrast to so-called structural scanning, it is functional imaging. In one out of four patients, findings from a PET scan can prevent the use of unnecessary surgery or unneeded therapy. We generally recommend high-quality cross-sectional imaging, typically a PET/CT scan.
The PET/CT is a combination of a PET scan and a CT scan, but a different type of CT scan that is often performed without contrast. Indeed, the CT part of a PET/CT does improve the accuracy of the PET scan, because it’s a combined scan that shows more anatomy or more structure, so it improves the accuracy of the PET scan. But it does not produce the same results as the contrast CT scan, unless you specify that you want contrast CT as part of the PET/CT.
Volumetrics is the other technique where the radiologist can almost perform virtual surgery, prior to the real surgery, to map out the remnant volume and calculate the volume. That’s a variation of the CT scan that is rarely needed, except for selected patients whose disease is borderline resectable status. High-quality intraoperative ultrasound is used by the surgeon to guide the surgery.
If the medical oncologist or community physician evaluates a potential candidate for surgical therapy, they should use imaging from a high-quality CT scan, and perhaps even a PET scan to determine whether the patient’s disease may be potentially resectable. In most of those cases, those imaging studies should be reviewed by an experienced hepatic surgeon. I think most patients with liver-only metastases or potential resectable liver metastases and resectable extrahepatic disease should be evaluated by an experienced team. We often use a combination of imaging studies done in the local community and some high-tech imaging done at the tertiary care center. The optimal management of patients with metastatic colorectal cancer should include a multidisciplinary team approach, which includes all the diagnostic and therapeutic options, including an experience liver surgeon. The most important factor is the experience of the surgical team.
