Colorectal Cancer 101: What You Need to Know

Mar 16, 2020


Colorectal cancer is diagnosed in about 140,000 patients annually in the United States, with twice as many people receiving a diagnosis of colon cancer than rectal cancer. 

Thankfully, there are multiple screening options for early detection and a growing range of treatment options. Dr. Tyler Kang, board-certified medical oncologist and hematologist at the Martin-O’Neil Cancer Center at Adventist Health St. Helena, gives an overview of this disease and what you need to know about screening and treatment.

Sobering statistics

Colorectal cancer is the third most common cause of cancer death in women and second most common in men, with nearly 50,000 deaths annually. The mortality rate has been declining year over year, although the number of patients diagnosed who are under age 50 is increasing at the same time. Colorectal cancer screening is proven to be effective in detecting disease at an earlier and curable stage thereby improving the overall death rate. Unfortunately, compliance with screening recommendations remains low—that means people are avoiding this important, potentially lifesaving screening.

Symptoms and diagnosis

The most common symptoms of colorectal cancer include change in bowel habits, rectal bleeding and anemia. Diagnosis requires examination of a tissue biopsy under the microscope to confirm presence of malignant cells. Further evaluation of the extent of disease (also known as staging) may be done with radiographic imaging using computed tomography (CT) or positron emission tomography (PET). 

Surgical treatment

For patients who do not have evidence of tumors outside of the colon confines, surgical excision (or surgical removal) of that portion of the colon helps treat the disease as well as complete the “surgical staging” of the cancer as examination of the lymphatic supply to that area of the colon will help determine if there are microscopic metastasis of cancer cells into the lymph nodes. The lymph system is a major part of the body’s immune system. Risk of cancer recurrence (when cancer occurs after a period of remission) is high if there is evidence of cancer cells in the lymphatic system. If this is the case, additional treatment after surgery (commonly called “adjuvant therapy”) would then be recommended.

Chemotherapy treatment

For those whose cancers have metastasized, or spread, to other parts of the body, surgical management will not be curative and therefore systemic therapy (treatment that will encompass the entire body) is preferred. This usually involves use of drugs that will stop cancer cells from continuing with their rapid cellular proliferation and are commonly called chemotherapies. Chemotherapies are outpatient treatments that are given on a recurring basis, and over time will help halt and even reverse cancer growth and often will alleviate symptoms related to metastatic disease. This does not cure the disease but will improve survival and with the goal of improving quality of life (palliation).

Targeted therapy and immune therapy

With better understanding of how cancers develop, we have learned that there are certain cancer pathways that affect growth of these abnormal cells and therefore can be targeted to further improve treatment outcome. In patients whose cancers lack mutations in a set of genes called RAS, they can respond to treatments called targeted therapies that utilize an inhibitor of the epidermal growth factor receptor (EGFR). 

Patients with cancers that have deficiency in DNA repair enzymes or their corresponding genes known as mismatch repair genes can respond to treatments known as immune therapies that target cancers by affecting their ability to evade the immune system. These newer treatments are not only effective, but they also come with much less toxicity to the patient and therefore conforms to the goal of palliative care and quality of life in individuals with advanced cancer.

The combination of these diagnostic and treatment modalities along with the multidisciplinary coordination of care between cancer specialists at the Martin O’Neil Cancer Center aims to provide the latest and most advanced treatments to our patients in the North Bay region. 

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