Original Article: Care of the Colorectal Cancer Survivor

Issue Date: March 1, 2018

See additional reader comments at: https://www.aafp.org/afp/2018/0301/p331.html

To the Editor: This article is well written and covers an important topic. Indeed, as cancer care continually improves, the ongoing needs of cancer survivors are poised to become a very important facet of primary care. However, the article omits a critical aspect of the topic: consideration of the role of genetic variation in the care of the cancer survivor.

Genetic variation in somatic (tumor) tissue alters the prognosis and treatment for a wide variety of cancers. This variation has important consequences for tumor recurrence surveillance, as well as the spectrum of short- and long-term adverse effects a survivor is likely to experience. Examples include changes in therapeutic approaches for chronic myelogenous leukemia with tyrosine kinase inhibitors, as well as use of gene expression platforms such as Oncotype DX and Mammaprint, which guide decisions about adjunctive (and often toxic) therapies for breast cancer. In colorectal cancer, testing patients for KRAS mutations may affect the choice of chemotherapy approaches and, likely, downstream recurrence risks and adverse effects.¹

The authors' statement that “colorectal cancer survivors should be screened [for secondary cancers] according to the same guidelines used for screening in average-risk persons” seems problematic without added qualifications. The Centers for Disease Control and Prevention estimates that as many as one in 20 colorectal cancers results from an underlying hereditary predisposition due to a mutation in key pathways related to oncogenesis. If a cancer survivor has a hereditary cancer syndrome, recommendations for screening for secondary cancers differ from those for the general population.²

In Reply: Thank you, Dr. Feero, for your thoughtful comments. Much of what you point out was simply beyond the scope of our article. For example, genetic tumor variations and chemotherapy choices fall more into the category of colorectal cancer treatment rather than guideline-based follow-up. I did not find current consensus guidelines that recommend altering follow-up schedules based on genetic tumor variation. This highlights the importance of the survivorship care plan, in which subspecialists can detail individualized follow-up schedules that may fall outside the usual guidelines for patients at average risk.

To clarify—and to avoid misunderstandings for clinicians caring for these patients—our article and the guidelines it summarized did not apply to patients with known hereditary cancer syndromes, including Lynch syndrome and familial adenomatous polyposis.