Abstract

Colorectal cancer is the 3rd commonly diagnosed cancer and the second cause of cancer related death in the USA every year (Guan, & Feudale, 2010). In 2008 cancer survey, 148,000 patients were diagnosed with cancer and 49,960 of people diagnosed died, thus, keeping cancer related death at a 33.5% mortality rate (Guan, & Feudale, 2010). The severity and stress caused by colorectal cancer are almost unbearable to the patient and family members involved. Recent studies showed that 6% of Americans will develop a form of colorectal cancer within their lifespan, and the disease usually manifest as multiple colon polyps within an individual in their 40’s or 50’s (Guan, & Feudale, 2010). Colorectal cancer may be caused or initiated by several factors, but one of the major factors is attributed to gene mutations. This case study examines the possibility of having a recessive MYH mutation for colorectal cancer, the possibility of developing colorectal cancer with a known MYH mutation, and advances possible preventative measures, cures or palliative therapy for the disease.

Cancer Case Study

Several factors associated with the onset of colorectal cancer is not limited to gene mutations, environmental factors such as radiation, red meat consumption, alcoholism and cigarette. In any case, the thought that a family member may have the disease inflicts excruciating pain, stress and fear to the person and family members in question. The disease may occur in a family that has never had any history of the disease, or occur as a result of familial and inherited disorder. Three known types of hereditary colorectal syndrome have been identified as familial adenomatous polyps (FAP), hereditary non-polyposis colon cancer (HNPCC) and the recently discovered autosomal recessive MYH polyposis syndrome (Cheadle, & Sampson, 2003).

In the case where the disease is non-hereditary, spontaneous mutations, virus infections, bacterial infections, environmental factors such as radiation or lifestyle, red meat consumption may cause the disease.  The risk of developing colorectal cancer is approximately 6% for an individual that never had a history of colorectal cancer in their family, and 18% for an individual with a first-degree relative who have had colorectal cancer. In the US, 5% of colorectal cancer cases are hereditary, and the number of colorectal cancers cases are increasing by 1% every year (Lee, 2012).

Base excision repair (BER), DNA glycosylase-MYH is associated with DNA damage repair and DNA protection from reactive oxygenation, hydroxylation and methylation (Cheadle, & Sampson, 2003). The MYH gene may cause colorectal cancer when a bi-allelic mutation in the BER DNA glycosylase MYH, occurs, thereby leading to an autosomal recessive syndrome. In MYH patients, 10-100 polyps could be present in the onset of the disease as early as age 40. However, the good news is that this form of colorectal cancer doesn’t have a multi-generational familial history polyposis or cancer because the gene mutation is a recessive trait. Using Mendelian’s genetics, MYH carriers, which means having heterozygous forms of the MYH allele, may result in a 25% chance of having an offspring with the disease. While a heterozygous (carrier) and homozygous (recessive) forms of the MYH allele gene crossing, may result in a 50% chance of having an offspring with the disease.

An auto-fluorescence imaging (AFI) technology has shown to have higher accuracy in detecting small-flat adenomas and non-granular laterally spreading tumors and should be followed up every 5-10 years for colonoscopy exam (Suzuki, Saito, Mutsuda, et al., 2011). Family with history of this disease should encourage their offspring to start testing for the disease 10 years earlier as recommended by the American Cancer Society before turning 40 years old. In addition, it is important to note that colorectal neoplasm is not solely based on genomic make up, but rather, its onset involves gene interaction with environmental factors such as unhealthy lifestyle, smoking, alcohol intake, radiation, and exposure to known carcinogenic chemicals.

Exposure to any of these factors may lead to an early onset of the disease, and may increase the chances of the invasive form of the cancer (Lee, 2012). Abdominal pain, fatigue, hematochezia are some of the symptoms and signs of colorectal cancer that should be monitored (Guan, & Feudale, 2010).  Nonetheless, the best possible cure for an early detected colorectal cancer is surgery (colectomy) or the use of bevacizumab (Avastin) therapy. In the case of aggressive colorectal cancer, combination of treatment such as colectomy, chemotherapy and bevacizumab may help for a palliative treatment, and to increase the time of progression of the disease or sometimes, progression free (Guan, H., & Feudale, F. 2010).

Furthermore, some lifestyle changes necessary to maintain a healthier lifestyle and proactively preventative measure include but not limited to nutrition rich in anti-oxidant, vegetables, fruits, fibers and active participation, in physical activities.

References

Cheadle, J., & Sampson, J. (2003). Exposing the MYtH about base excision repair and human inherited disease. HMG, 12(2), 159-165. DOI: 10.1093/hmg/ddg259. Retrieve from http://hmg.oxfordjournals.org/content/ 12/suppl_2/R159.full.pdf.
Guan, H., & Feudale, F. (2010). Is bevacizumab plus chemotherapy superior to chemotherapy alone in treatment of metastasic colorectal cancer?. IJAPA, 7(2). 26. Retrieve from http://web.ebscohost.com.ezp.waldenulibrary.org/ehost/detail?sid=933199e8-ac24-46d9- bec9- ef34fa7af6cc%40sessionmgr113&vid=1&hid=105&bdata= JnNpdGU9Z Wh vc 3QtbGl2ZSZzY29wZT1zaXRl.
Lee, D (2012). Colon Cancer, The Genetic Factor. Medicinenet.com. Retrieve from http://www.medicinenet.com/script/main/art.asp?articlekey=46105.
Suzuki, H., Saito, Y., Mutsuda, T., et al., (2011). Prospective Case Study on Characterization of Colorectal Adenomas Comparing AFI with NBI. DTE, 2011 (2011). doi:10 .1155 /2011 /963618. Retrieve from http://www.hindawi.com/journals/ dte/2011/963618/.