although priapism has been reported as a complication of malignant tumor metastasis , leukemia , sickle cell disease , embolism and spinal canal stenosis [ 1 , 2 , 3 , 4 , 5 ] , there are few reports of priapism as a complication of colorectal cancer in the absence of penile metastasis . here
we report a patient with rectal cancer with no penile metastasis in whom chemotherapy resulted in an improvement of priapism .
a 65-year - old man was admitted to our hospital for priapism with tenderness of the penis and dysuria .
enhanced abdominal computed tomography demonstrated metastatic tumors in the liver , lung , sacrum ( fig .
ultrasonography of the penis revealed no tumor and normal blood flow in the penis vessel .
chemotherapy ( folfox4 ; levofolinate 25 mg , fluorouracil 250 mg , oxaliplatin 100 mg ) was administered , and although the primary rectal cancer showed no change ( fig .
brain or splenic metastasis and hypercalcemia arising from bone metastasis have been reported as rare complications of colorectal cancer [ 6 , 7 , 8 ] .
chemotherapy regimens for metastatic colorectal cancer include fluorouracil , leucovorin , either oxaliplatin or irinotecan , and the vegf inhibitor bevacizumab .
priapism is a complex involuntary behavioral response that depends on the integration of vascular , endocrine and neurological mechanisms .
stimuli for erection can be classified as psychogenic and reflexogenic . when visceral nerves at the sacrum are stimulated electrically , this results in persistent penile erection .
nervi erigentes. a second , thoracolumbar erection centre at the level of t12l1 plays a role in psychogenically mediated erections via sympathetic efferent fibers .
disturbances in penile blood flow due to metastasis in the penis have been reported to cause priapism . in this case , the cause of priapism might have been micrometastasis in the penis , metastatic tumors that affected the spinal cord , or continuous stimulation of nervi erigentes by a metastatic tumor .
chemotherapy , which reduced the metastatic tumor in the sacrum , may also have reduced the level of nervi erigentes stimulation .
the results from this case suggest that chemotherapy can be effective for treating rare complications of rectal cancer such as priapism .
 a 65-year - old man was admitted with penile tenderness and dysuria due to priapism . enhanced computed tomography revealed metastatic tumors in the liver , lung , sacrum and lymph nodes . 
 advanced rectal cancer , detected by colonoscopy as a primary tumor , was treated with chemotherapy ( folfox4 ) . 
 although the rectal cancer showed no change , five months of chemotherapy improveid the priapism , suggesting that chemotherapy can improve rare symptoms of rectal cancer . 
Introduction
Case Report
Discussion