- TABLE OF CONTENTS
- Introduction
- Colorectal Cancer: The Facts
- Stages of Colorectal Cancer
- The Animal Study
- How Sildenafil Works
- Sildenafil vs. Linaclotide
- What’s Next?
- If Erectile Dysfunction Is Your Problem
Introduction
In the two decades since its introduction, Viagra, or more specifically its active ingredient, sildenafil citrate, has been found to have a number of health benefits above and beyond its ability to temporarily overcome the symptoms of erectile dysfunction.
For years, sildenafil has been prescribed at lower doses as a treatment for pulmonary arterial hypertension, a form of high blood pressure that targets the lungs. It has also been found useful in improving athletic performance at extremely high elevations and is being explored as a promising new treatment for birth asphyxia, which is diagnosed most often in premature newborns.
Oncology research has shown that sildenafil can improve the efficacy of chemotherapy drugs when the two are used together. Although the precise effects of sildenafil for this purpose are not yet clearly understood, it appears to make it easier for chemotherapy to target cancerous cells.
Sildenafil shrinks ‘the whole proliferating compartment in an area of our body that directly deals with whatever we put in our mouths and normally experiences high cell turnover. Proliferating cells are more subject to mutations that cause cancer.’
— Darren D. Browning
Cancer Researcher
Recent research has revealed that small daily doses of sildenafil significantly reduce the risk of colorectal cancer in laboratory animals that have been genetically modified to develop abnormally high levels of colorectal polyps. Left untreated, such polyps quite often turn cancerous. So promising have been these early animal tests that clinical trials with humans are expected to get underway soon.
Colorectal Cancer: The Facts
The American Cancer Society estimates that one in every 22 American men will develop colorectal cancer during their lifetime. The incidence in women is only slightly lower, occurring in one of every 24 females. The incidence of this cancer increases with age: The median age for diagnosis in males is 68, compared with a median age of 72 in women. This widespread form of cancer targets the colon or rectum, which together are known as the large intestine.
The ACS reports that colorectal cancer is the third biggest cause of cancer deaths in the United States and is expected to account for roughly 50,000 deaths in 2018. Across all ethnic and racial demographics, the cancer is most widely diagnosed among non-Hispanic blacks.
According to the ACS, colorectal cancer usually begins with the development of a non-cancerous polyp on the inner lining of the colon or rectum. The most common form of colorectal polyp is known as an adenomatous polyp, or adenoma. “Although all adenomas have the potential to become cancerous,” says the ACS, “fewer than 10 percent are estimated to progress to invasive cancer.” However, the larger an adenoma grows, the greater the risk that it will turn malignant.
Stages of Colorectal Cancer
The severity of a colorectal cancer diagnosis depends to a very large extent on the stage of cancerous development at the time it is diagnosed. The National Cancer Institute recognizes five distinct stages of colorectal cancer development. Stage 0, also known as cancer in situ, exists when abnormal cells develop in the colon wall’s innermost layer, known as the mucosa.
At Stage I, colorectal cancer has spread to the colon wall’s submucosa, the layer of tissue directly beneath the mucosa, and possibly the muscle wall of the colon wall. Stage II has three distinct substages: Stage IIA, in which cancer has spread to the outermost layer, or serosa, of the colon wall; Stage IIB, cancer has spread through the serosa but not yet affected nearby organs; and Stage IIC, in which cancer has fully penetrated the serosa and begun to affect nearby organs.
Stage III is also divided into three substages, each of which is defined by the number of lymph nodes to which cancer has spread. Stage IIIA exists when cancer has spread to at least one but no more than three nearby lymph nodes. Stage IIIB occurs when cancer has spread to at least four but not more than six lymph nodes. Stage IIIC defines cancer that has spread to seven or more lymph nodes.
Stage IV is divided into two substages. In Stage IVA, cancer may have spread to nearby organs and/or lymph nodes but has also spread to at least one distant organ or lymph node. Stage IVB occurs when cancer has spread to more than one organ distant from the colon or into the lining of the abdominal wall.
The Animal Study
Conducted by researchers at Augusta University and Georgia Cancer Center, which is based at the university, this study sought to determine the effects of sildenafil on laboratory mice genetically engineered to increase their risk of colorectal cancer. Animals were given small amounts of sildenafil daily in their drinking water.
Mice treated with sildenafil were 50 percent less likely to develop polyps than those control animals that did not get sildenafil. In sildenafil-treated mice that did develop polyps, the polyps were less proliferative, more differentiated, and less inflamed. Findings from the animal study were published in the July 2017 issue of “Cancer Prevention Research.”
How Sildenafil Works
In Viagra, the first of the so-called PDE5 inhibitors, sildenafil temporarily sidelines the phosphodiesterase-5 enzyme, which otherwise interferes with optimal blood flow by prematurely breaking down a substance known as cylclic guanosine monophosphate, or cGMP. Scientists have determined that higher levels of cGMP in the colon also reduce cell proliferation in the gastrointestinal tract, thus suppressing the development of polyps that could eventually turn cancerous.
Sildenafil vs. Linaclotide
At the same time they were evaluating the effects of sildenafil in suppressing colorectal polyp development, researchers also looked at the ability of linaclotide to achieve the same goal. They found linaclotide as or even slightly more effective than sildenafil at reducing the development of colorectal cancers. However, the side effects of linaclotide — severe diarrhea — make it a less satisfactory candidate for use in humans. By contrast, the small doses of sildenafil needed to suppress polyp development are unlikely to cause any significant side effects at all.
What’s Next?
The promising results from the animal study lay the foundation for human clinical trials to see if daily low-dose sildenafil treatment produces the same results in human study participants. Those studies, according to reports, will likely focus on people who have been found to be at a high risk of colon cancer. Asked to evaluate the findings from the animal study, lead author Darren D. Browning said sildenafil shrinks “the whole proliferating compartment in an area of our body that directly deals with whatever we put in our mouths and normally experiences high cell turnover. Proliferating cells are more subject to mutations that cause cancer.”
If Erectile Dysfunction Is Your Problem
Despite the growing recognition of its additional medicinal properties, sildenafil is still best known as the active ingredient in Viagra, the first of the oral ED drugs to hit the market. Under current U.S. regulations, you will need a prescription to purchase Viagra or any of the other PDE5 inhibitors on the market.
If you have a doctor’s prescription and would like to take advantage of the convenience of online ordering, consider using the services of eDrugstore.com, a reliable online facilitator since the late 1990s. Simply fax your prescription or scan and email it along with your order to eDrugstore. Alternatively, you can ask eDrugstore to set up a complimentary online consultation for you with one of its team of licensed U.S. physicians.
If the doctor determines that you are an appropriate candidate for the drug, a prescription will be authorized. To learn more, click here to visit eDrugstore’s Erectile Dysfunction page.
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