Penile metastasis in rectal cancer with pathologic complete response after neoadjuvant chemoradiotherapy: The first case report and literature review

RATIONALE: Penile metastasis in rectal cancer is very rare and often originates from prostatic or bladder cancer. The prognosis of penile metastasis is poor and its treatments are more often palliative than curative due to association with disseminated metastases. Pathologic complete response (pCR) in rectal cancer with neoadjuvant chemoradiotherapy (CRT) has been shown to be surrogate marker of favorable long-term outcomes and currently has no report of penile metastasis. Here, we first report isolated penile metastasis in rectal cancer with pCR after neoadjuvant CRT. PATIENT CONCERN: The patient was a 74-year-old male with metastasis to the glans penis from rectal cancer diagnosed 9 months after abdominoperineal resection. Physical examination revealed palpable multiple nodules on the glans penis. DIAGNOSIS: Penile biopsy revealed metastatic carcinoma from the rectal cancer. INTERVENTION: Chemotherapy was started as soon as possible, because patient suffered urinary discomfort by rapid growing metastatic lesions. He is currently receiving palliative chemotherapy with modified FOLFOX-6 (mFOLFOX-6; oxaliplatin with 5-fluorouracil and folinic acid) plus bevacizumab. OUTCOME: The patient is still alive 4 months after diagnosis with markedly decreased metastatic lesions. LESSON: We propose that although penile metastasis in rectal cancer with pCR after preoperative neoadjuvant CRT is extremely rare, it might help to start early palliative chemotherapy and clinicians should be aware of this possibility.