Colorectal Cancer: Critical Preventative Care and Dan "Dry Dock" Shockley: Hereditary Colon Cancer Warrior
The overall lifetime risk of colon cancer in the United States is 1 in 23 for men and 1 in 25 for women. Colorectal cancer is any cancer that occurs anywhere within the large intestines (the colon) down to the rectal cavity. These cancers can present with abnormal growths called polyps that vary dramatically in severity from one benign growth to hundreds of cancerous polyps.
According to the CDC, 90 percent of colorectal cancer cases occur in those age 50 and older. For those without an increased risk, the best way to screen for abnormal growths in the colon is through a colonoscopy at age 50, and then to repeat screening every decade (or sooner if symptoms present).
Of those diagnosed with colorectal cancer, around 70-80% of cases have no specific cause or family history and are considered sporadic. Therefore, it is critical for everyone to begin colonoscopy screenings at age 50, to catch cancer before it can start.
The average person can reduce their risk by taking care of their health and staying up to date on their preventative screenings. Some individuals may have increased risk factors outside of their control that may warrant additional preventative healthcare.
Colorectal cancer can grow anywhere within the large intestines down to the rectum.
Controllable factors that may reduce your risk:
- A diet high in fruits and vegetables
- A diet low in animal fats and fried foods
- Avoiding alcohol and tobacco
- Being physically active
Conditions that may increase your risk:
- Type 2 Diabetes
- Inflammatory Bowel Disease (Crohn’s Disease and Ulcerative Colitis)
- A personal or family history of colorectal polyps or colorectal cancer
- A personal or family history of a hereditary cancer syndrome
What You Need to Know About Hereditary Colon Cancer:
Most pertinent among those with an increased risk are those with a known or suspected familial or hereditary colon cancer syndrome. The differentiation may seem confusing, but simply put, a familial colon cancer is when cancer seems to run in the family, but there is no genetic explanation. A hereditary cancer syndrome is when an individual has an identified change in a specific gene that is known to dramatically increase personal risk for colorectal cancer. It is estimated that out of all colorectal cancer diagnoses, 2-10% of those cancers are hereditary forms. Hereditary cancer syndromes can increase a personal risk to almost 100% in some cases, so identifying individuals that may have hereditary syndromes is critical so that cancer occurrences can be prevented with additional screenings, surgeries, or treatments. Equally as important, if a person can identify if they have a hereditary cancer, potential family members at risk can also be identified and provided with life-saving care. Those recently diagnosed with colon cancer may benefit from talking to a genetic counselor to evaluate whether to undergo genetic testing for hereditary cancer syndromes.
Major Categories of Hereditary Colon Cancer
Hereditary Non-Polyposis Colorectal Cancer (HNPCC) and Lynch syndrome
o Lifetime colorectal cancer risk is estimated to be about 80%
o Preventative measures can include annual colonoscopy beginning at age 20. Screenings for additional cancers are also needed.
Familial Adenomatous Polyposis (FAP)
o Lifetime colorectal cancer risk is essentially 100% without surgical intervention.
o Preventative measures can include annual colonoscopy beginning at age 10-12; onset of polyps begins on average around age 16. Screenings for additional cancers are also needed.
Attenuated Familial Adenomatous Polyposis (AFAP)
o Lifetime colorectal cancer is estimated to be between 70-100%* without surgical intervention.
o Preventative measures can include annual colonoscopy beginning in the teenage years depending on the case; onset of polyps tends to occur later in life than in FAP and with fewer adenomas. Screening for additional cancers are also needed.
* Quantitative data differentiating AFAP from FAP is scarce due to how rarely AFAP presents.
MUTYH – Associated Polyposis (MAP)
o Lifetime colorectal cancer risk is estimated to be up to 80%.
o Preventative measures can include annual colonoscopy starting at age 21 depending on family history.
9 Year AFAP Warrior - Dan “Dry Dock” Shockley:
Dan “Dry Dock” Shockley spent 22 years on active duty serving in the United States Navy from 1981 to 2003. After multiple deployments in the Persian Gulf, Dan retired and moved to Hawaii. After an unintentional 14lb weight loss in 2012, Dan underwent his first colonoscopy at the age of 51. His physician reported 100 polyps embedded throughout the colon, rectum and anus. Of the 100 polyps, one was causing an 80% blockage of the ascending colon. Surgery revealed that polyp was an 8cm tumor, stage 0. The tumor and associated lymph nodes were successfully removed during the surgery.
Throughout Dan’s healthcare journey he expected candid and honest conversations from his medical team. For Dan, tackling his cancer with a positive attitude meant utilizing all resources available to him. Although Dan had no family history of colorectal cancer and his siblings were well, the number of polyps indicated a concern for a contributing genetic factor. This is when Dan was referred to a clinical genetic counselor. To better understand his care plan, Dan decided to proceed with genetic testing from the closest laboratory, which was in California. While his medical team expected a positive result for FAP, Dan’s results came back six weeks later with an even rarer condition, AFAP. The treatment he needed would require he leave Hawaii to see specialists at the Stanford University Cancer Center.
This diagnosis awoke an energy within Dan—he even describes it as “excitement”. He knew from his military background that he had been training his whole life to adapt to any challenges that were presented and that this was something he could face. Dan learned everything he could about AFAP, but with the rareness of his condition, he has yet to meet anyone else with his diagnosis. Based on his prognosis, he and his care team opted for a necessary total proctocolectomy with permanent ileostomy; in other words, removal of the entirety of the large intestines and rectum and use of a permanent ostomy, which allows for the rerouting of waste.
As Dan recovered from his surgery, he knew his purpose was to spread awareness of AFAP and FAP, ostomy awareness, and how critical early detection and screening are in stopping colorectal cancer. In 2013, Dan met the father of hereditary cancer syndromes, Dr. Henry Lynch, at the University of Hawaii Cancer Center. Dr. Lynch, having joined the Navy at age 16 using false identification, connected with Dan’s determined, confident spirit. The bond they formed over their shared interest in Dan’s condition as well as their friendship fueled Dan to continue Dr. Lynch’s legacy after his passing in 2019.
Solidifying his commitment, Dan created his own acronym for AFAP: Always Forge Ahead with a Purpose. As Dan continues staying up to date on AFAP research internationally and advocating for the importance of early detection, he has stayed busy with his efforts to have the fourth week of March designated as Hereditary Colon Cancer Awareness Week. His work has received sponsorship from governors across the country and he has no intentions of stopping anytime soon.
As research continues, Dan hopes to see an increase in accessibility to FAP and AFAP support groups as well as seeking out and collaborating with as many organizations as possible to provide encouragement for preventative colorectal cancer screenings worldwide.
Pictured: Dan “Dry Dock” Shockley (left) with Dr. Henry Lynch, (right) the “Father of Hereditary Cancer Detection and Prevention”
Contact Clover Genetics with any questions about hereditary cancer syndromes or your personal risk.
Resources:
“Basic Information About Colorectal Cancer.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 8 Feb. 2021, www.cdc.gov/cancer/colorectal/basic_info/.
Burt, Randall & Randall, Dr & Burt, W. (2009). Genetics and Inherited Syndromes of Colorectal Cancer. Gastroenterology & Hepatology Volume. 5.
“Cancer Genetics.” Northwestern Medicine I Clinical Genetics, clinicalgenetics.nm.org/cancer-genetics.html.
“Colon Cancer: Symptoms and Causes.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 16 Mar. 2021.
“Colorectal Cancer Risk Factors: Hereditary Colorectal Risk Factors.” American Cancer Society, www.cancer.org/cancer/colon-rectal-cancer/causes-risks-prevention/risk-factors.html#written_by.
“Getting to the Bottom of Colorectal Cancer Myths.” Misconceptions About Colorectal Cancer – San Diego –, 9 Mar. 2020.
“Hereditary Colon Cancer: Guide for Health Pros: Guide to Hereditary Cancer for Health Pros: UT Southwestern Medical Center.” Guide to Hereditary Cancer for Health Pros, UT Southwestern Medical Center.
Jasperson, Kory W et al. “Hereditary and familial colon cancer.” Gastroenterology vol. 138,6 (2010): 2044-58. doi:10.1053/j.gastro.2010.01.054
Testa, Ugo et al. “Colorectal cancer: genetic abnormalities, tumor progression, tumor heterogeneity, clonal evolution and tumor-initiating cells.” Medical sciences (Basel, Switzerland) vol. 6,2 31. 13 Apr. 2018, doi:10.3390/medsci6020031