Colorectal Cancer

What is colorectal cancer?

The colon is the part of the digestive system where the waste material isformed. The rectum is the end of the colon adjacent to the anus which stores waste material. Together, they form a long, muscular tube called the large intestine (large bowel).

anatomy_colon

Figure 1: Anatomy of  the colon and rectum.

Tumors of the colon and rectum are growths arising from the inner wall of the large intestine. Together they are known as ‘colorectal cancer’.

What is stage 4 colorectal cancer?

When a cancer arising from the colon or rectum has spread to other organs like the liver, the lungs, the peritoneum , distant glands, it is know stage 4 colorectal cancer

What is Colorectal PC (Peritoneal carcinomatoses)?

Presence of cancer in the peritoneum in colorectal cancer is known as Colorectal PC. In colorectal cancer (cancer of the large bowel), peritoneal cancer will develop in about 15% of the patients.

What is the treatment of Colorectal PC?

There are 3 important components of treatment.

  1. Cytoreductive surgery
  2. HIPEC
  3. Systemic (intravenous chemotherapy). All three components of treatment are essential for good long term results. Some patients may get systemic chemotherapy first followed by cytoreductive surgery and HIPEC or vice versa in others.

Which Patients of Colorectal PC can be treated?

It is important to know the extent of disease. A PET CT scan or CT scan may be done to see

  1. Spread of cancer to other organs
  2. Extent of spread in the peritoneal cavity

 1. Spread to other organs

Patients with peritoneal implants often have seeding in the liver or lungs. In 3% of all patients however, seeding is limited to the peritoneum. It is for this subgroup of patients  cytoreductive surgery and HIPEC may be an option. In some selected patients with 1-3 tumors in the liver and peritoneal cancer, surgery could still be possible.

2. Extent of spread in the peritoneal cavity

It is important to know the extent of spread of the tumor in the peritoneal cavity. The surgeon measures the amount of cancer in 13 different regions of the abdomen and gives each region a score from 1 to 3. These scores are added to a global score (Sugarbaker’s  Peritoneal Cancer Index).

PCI

In colorectal PC a PCI score of >20 indicates that surgery and HIPEC may not be useful. These patients are treated with systemic chemotherapy alone. In patients who have a very good resonse, surgery and HIPEC may be attempted. The score also tells us about the prognosis. The less the score, the better the outcome.

What is the benefit of cytoreductive surgery and HIPEC in colorectal PC?

Before Cytoreductive surgery and HIPEC became popular, the only treatment for colorectal PC was systemic chemotherapy. With this treatment most patients survived a few months to one year. Cytoreductive surgery and HIPEC increases the survival in these patients  to 3-5 years and even more in some of them. Extent of disease spread is a key factor that determines the outcome