Oncologist Answers Most Asked Questions About Colorectal Cancer

When someone is diagnosed with colorectal cancer, they often have more questions than answers. Understanding biomarker testing, treatment options, clinical trials and what to expect throughout the cancer journey can help patients make informed decisions about their care.

To help address some of the most common concerns, CURE® spoke with Dr. John Marshall of MedStar Georgetown University Hospital, who also serves on the board of the Colorectal Cancer Alliance. Marshall shared insights on how colorectal cancer treatment is evolving and what patients should know about advocating for themselves.

How Is Biomarker Testing Changing Colorectal Cancer Treatment?

For many years, colorectal cancer was treated as a single disease. Today, doctors know that colorectal cancer consists of multiple subtypes driven by different genetic changes.

Biomarker testing helps identify these differences by looking for molecular characteristics such as microsatellite instability (MSI), BRAF mutations and RAS mutations. These results can help doctors select targeted therapies and immunotherapies that may be more effective for specific patients.

Marshall compares biomarker-driven treatment to turning off a light switch rather than simply breaking a light bulb.

"Most of the drugs we have just break the light bulb," he explained. "But now with biomarkers, we actually have drugs that will go over there and turn the light switch off in a targeted, precise way."

He emphasized that patients should discuss biomarker testing with their healthcare team and understand their tumor's molecular profile as early as possible.

"We are not seeing the kind of uptake of testing that we would like," Marshall said. "Patients out there, if you don't know what your biomarkers are, you need to."

What Role Do Targeted Therapies and Immunotherapy Play in Colorectal Cancer?

While chemotherapy remains an important treatment option, targeted therapies and immunotherapies are becoming increasingly important in colorectal cancer care.

Researchers are learning more about the genetic pathways that drive cancer growth and the mechanisms tumors use to evade the immune system. These discoveries are leading to new treatments designed to attack cancer more precisely.

According to Marshall, there is significant activity in both areas, with new therapies continuing to emerge and additional treatment approvals expected in the future.

"We're getting smarter and smarter about what's actually broken behind the wall," Marshall said. "Can we fix the wire so that it's running right, or how is the cancer hiding from the immune system, and can we, in fact, unveil the cancer, so that your own immune system can take care of cancer?"

Determining which patients may benefit from these treatments depends largely on biomarker testing and understanding the molecular characteristics of an individual's cancer.

Should I Get a Second Opinion After a Colorectal Cancer Diagnosis?

Marshall believes most patients can benefit from hearing from more than one expert.

Second opinions can help confirm a treatment plan, provide reassurance and identify additional options such as clinical trials. They may also offer specialized insights into treatment sequencing, dosing adjustments or emerging therapies.

"I think all patients should probably talk to more than one doctor," Marshall said.

As cancer care becomes increasingly complex, consulting a specialist who focuses on colorectal cancer may provide valuable perspectives beyond routine treatment recommendations.

Sometimes a second opinion opens the door to clinical trials. Other times it offers insights into treatment decisions that may improve a patient's experience and outcomes.

"Second opinions are routine, and I think most patients get them," Marshall said.

Why Do Some Patients Still Face Barriers to Precision Medicine?

Although precision medicine has advanced rapidly, access to testing and specialized care remains inconsistent.

One challenge is determining which tests should be performed and when. Patients may require tissue-based testing, blood-based testing or additional biopsies depending on their situation.

Marshall noted that selecting the right test is similar to choosing the right imaging study.

"Some people like CAT scans, and some people like PET scans, and some people like MRIs," he said. "They're kind of the same, but they're also pretty different."

Likewise, different molecular tests provide different information, and ensuring patients receive the most appropriate testing remains an important part of personalized care.

What Should I Do After a Colon Cancer Diagnosis?

Marshall encourages newly diagnosed patients to learn as much as they can about their disease.

Patients should understand:

• What stage their cancer is
• Where the tumor is located
• The genetic characteristics of the cancer
• Whether a cure may be possible
• Available treatment options
• Potential clinical trial opportunities

"Any patient diagnosed with any cancer needs to learn as fast as they can everything they can about their disease," Marshall said.

The more informed patients are, the better equipped they are to advocate for themselves and participate in treatment decisions.

"It's a big ask to know all of that," Marshall acknowledged. "But patients can be great advocates for themselves."

How Do Doctors Decide Which Colon Cancer Treatment Is Best?

Treatment decisions depend on several factors, including the stage of the disease, where the cancer is located and the molecular characteristics of the tumor.

Doctors also consider a patient's overall health, support system and personal goals.

"There is a different treatment strategy for almost every patient, depending on the lay of the land," Marshall said.

While clinical research and treatment guidelines inform decisions, care plans remain highly individualized.

"There is no AI formula that you can plug into and spit out the right answer for every individual patient," Marshall said. "We need to fold in what that patient brings to the table."

What Questions Should I Ask My Doctor About Colorectal Cancer?

Patients should feel comfortable asking questions and actively participating in discussions about their care.

Marshall recommends asking:

• Why is this treatment being recommended?
• Are there alternative treatment options?
• Should I undergo biomarker testing?
• Am I eligible for a clinical trial?
• What are the goals of treatment?
• Would a second opinion be helpful?

He also encourages patients to request written information whenever possible and seek out trusted educational resources.

"It's perfectly appropriate to challenge and ask your medical team what they know and why," Marshall said.

"Make sure that you walk out of that room knowing everything you can know. Get as much as you can in writing, do a little digging on your own, get that second opinion, and I think you'll be pleased you did. You'll be a smarter consumer, and you'll get a better outcome."

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