(This version of the story corrects measurements cited in paragraph seven)
By Andrew M. Seaman
(Reuters Health) - After prostate removal for cancer, men sometimes complain to their doctors that their penis shrank, but a new study from Japan suggests they should not lose hope.
Following men for up to two years after surgery, researchers found the patients' penises were shortest a few days after their procedures. Penis lengths generally returned to normal after one year, however.
The study's lead author said the research was started after encountering a few patients complaining of penis shortening after prostate removal, which is known medically as a radical prostatectomy.
Past reports mentioned shortened penises after prostate removal, but the results were a bit different, said Dr. Yoshifumi Kadono, of Kanazawa University Graduate School of Medicine Science.
"Therefore, we started our study to obtain our data," he told Reuters Health.
For the new study, the researchers measured the penis lengths of 102 men before having their prostates removed and then at 10 days after surgery and again one, three, six, nine, 12, 18 and 24 months later.
The men's stretched penis lengths were shortest 10 days after surgery, when measurements were an average of about 1.99 centimeters (0.78 inches) shorter than before prostate removal.
By the one-year mark, the men's penises generally returned to original lengths, which averaged about 11.72 centimeters (4.61 inches), according to the results in BJU International.
The researchers wanted to know what caused the shortening and if any particular variable, such as the size of a man's prostate gland, would predict which men would experience this effect.
Based on magnetic resonance imaging (MRI)of the patients, the researchers noticed some internal changes. Specifically, the portion of the urethra directly below the bladder moves up into the body after surgery, but moves back down after some time.
"However, further research is needed to elucidate long-term changes of (penis length) with respect to the influence of sex hormones or changes in penile blood flow after (radical prostatectomy)," said Kadono.
The new findings may be useful for men who have low-to-moderate self esteem tied to their perceived lost penis length after their surgery, he added.
The findings may not represent reality for all men, however.
Most men will have some penis length loss after surgery and sometimes that will be permanent, said Dr. John Mulhall, who is director of the Male Sexual and Reproductive Medicine Program at Memorial Sloan Kettering Cancer Center in New York.
"If you have documental length loss at six months, then you shouldn’t expect that to improve at 12 months," said Mulhall, who wasn't involved in the new study.
He told Reuters Health that loss of penis length can be attributed to two issues. For example, muscle contractions may pull the penis into the body, but that relaxes over time. Men may also experience after surgery the loss of erection tissue.
"Once that muscle degenerates, it’s gone," he told Reuters Health.
Dr. Drogo Montague, who wasn't involved in the new study but often treats urological issues in men after prostate removal, also said some penises may appear shorter after surgery due to scar tissue that builds up when men have sex with partial erections.
The patients included in the new study would generally be considered to be normal weight, noted Montague, who is a professor of surgery at the Center for Genitourinary Reconstruction Glickman Urological and Kidney Institute Cleveland Clinic in Ohio.
"So these findings won’t necessary be generalizable because of the prevalence of obesity," he told Reuters Health.
Mulhall said medications like Viagra and Cialis - known as PDE5 inhibitors -are shown in previous research to guard against lost penile length after prostate removal.
In addition to PDE5 inhibitor, Montague said men can get prostheses and other interventions to strengthen their penises.
SOURCE: bit.ly/2lctQla BJU International, online February 8, 2017.