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Diagnosis and Treatment

Dear Iris: Why Wasn’t I Prescribed That Medication?

Dear Iris,

I was recently diagnosed with colon cancer and saw a commercial for Keytruda. I’d like to switch to this medication, but my oncologist says I need to continue getting the drugs I am on. Keytruda sounds so much better than the treatment I get. Why do you think he won’t let me switch?


Dear R,

The type of cancer treatment you’re prescribed is specific to your cancer. Factors such as tumor type, genetics, and stage of disease all play a role in helping your oncologist decide the best way to treat your cancer.

A shorter way of saying this is: not all chemotherapy/immunotherapies/targeted therapies can be used to treat colon cancer.

When deciding on the best treatment plan for you, oncologists perform a thorough physical exam to establish your overall health. This information, coupled with information specific about your cancer and your preferences/wishes, helps your oncologist determine the best course of action.

The plans developed by your oncologist are also guided by the National Comprehensive Cancer Network (NCCN), which has established guidelines for the most effective treatments for each diagnosis based on extensive clinical trial data. This is generally referred to as “standard of care.”

So, does this mean that you’ll never be able to be on a treatment like Keytruda? Not exactly.

Currently, there are over 1,000 clinical trials all over the world testing different types of treatment modalities for colon cancer (and other cancer types as well). The data collected from these clinical trials help show whether a chemotherapy/immunotherapy/targeted treatment can be used for different types of cancers and its effectiveness. As these studies continue to publish their results/data, we will see changes in the way certain cancers are treated and how these medications are used.

If you and your oncologist feel your treatment is not as effective as imagined, you may decide to change the course of treatment. Just remember that seeing an ad for one medication doesn’t mean it’s more effective than another. The best decision is always going to be based on multiple factors that are specific to you.

Missed last week? Dear Iris: Feeling Grateful Feels Impossible

Jenna Rush, RN

Oncology RN Team Lead

Iris Oncology

Jenna Rush worked as a nurse in pediatrics and cardiac/thoracic and vascular surgery before finding her home in oncology nursing in 2012. Jenna is particularly passionate about patient education, advocating for patients, and supporting holistic care models. Second to being a mother, oncology nursing is her life's highest purpose — caring for people during some of the most difficult, scary, and uncertain times of their life.

This article meets Iris standards for medical accuracy. It has been fact-checked by the Iris Clinical Editorial Board, our team of oncology experts who ensure that the content is evidence based and up to date. The Iris Clinical Editorial Board includes board-certified oncologists and pharmacists, psychologists, advanced practice providers, licensed clinical social workers, oncology-certified nurses, and dietitians.