Viagra an anti-cancer drug? Erectile dysfunction medications may help treat esophageal cancer


LONDON — Drugs which are routinely used to treat tens of millions of men for erectile dysfunction may also assist in the arduous and slow chemotherapy treatment of esophageal cancer, new research suggests.

Research funded by Cancer Research UK and the Medical Research Council finds that phosphodiesterase type 5, or PDE5 inhibitors, help to shrink tumors in the esophagus and reverse a patient’s resistance to chemotherapy. Numerous PDE5 inhibitors used to treat erectile dysfunction including sildenafil (Viagra), vardenafil (Levitra, Staxyn), tadalafil (Cialis), and avanafil (Stendra) may now help esophageal cancer patients.

These ED drugs can potentially work in tandem with chemotherapy to target cancer-adjacent fibroblasts (CAFs), which are in and around the edges of esophageal tumors.

Esophageal tumors often worsen rapidly because the throat microenvironment (area immediately surrounding the tumor) consists of CAFs, malignant molecules and tainted blood vessels which form a “protective cloak” against chemotherapy.

Esophageal cancer has poor survival rates

Some esophageal cancer studies have found that only one in 10 patients live for more than 10 years after diagnosis. This morbid statistic is due in part to esophageal tumors often showing zero response to chemotherapy due to the protective microenvironment. However, the researchers stress that this mortality and survival data is hard to estimate because of poor response rates and widely varying diagnosis timelines.

Professor Tim Underwood of the University of Southampton led a team which treated an esophageal tumor microenvironment with PDE5 inhibitors. Nine of the 12 samples tested showed positive signs that the tumor became “sensitive” to the ED drug treatment.

Half of American men take ED drugs

Additional tests involving mice implanted with chemotherapy resistant esophageal tumors found no adverse side-effects to the PDE5 treatment. After years of helping with the physiological aspects of erectile dysfunction, researchers say they are hopeful that continued testing may ease chemotherapy for a multitude of cancer patients. ED drugs including Sildenafil (Viagra) enhance the effects of nitric oxide, a natural chemical the body produces which relaxes muscles in the penis.

More than 50 million men in America routinely ingest these drugs for physiological treatment. Psychological causes of erectile dysfunction, however, include counseling or therapy which targets potential root causes such as stress or anxiety.

Several patients diagnosed with esophageal cancer, as well as researchers involved with these latest clinical trials, expressed their optimism that the PDE5 inhibitor drugs may soon help ease chemotherapy treatment for others.

“Chemo generally doesn’t work that well on my kind of esophageal tumor so I knew it couldn’t get rid of the tumor completely, that it could only shrink it with the hopes of making surgery more effective,” says Nicola Packer, a human resources manager from England, diagnosed with a condition adjacent to esophageal cancer at age 53, in a statement.

“The chemo was draining and each week they would tell me it was shrinking my tumor, but slowly. The anxiety you feel after going through chemotherapy and then having to wait through the weeks of recovery before you can have surgery, knowing that the chemo could only do so much is overwhelming,” Packer continues. “Research like this that could mean people like me can have a better response to chemotherapy is incredibly important.”

The study is published in the journal Cell Reports Medicine.

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