Surgery, radiotherapy, chemotherapy, targeted therapy, and immunotherapy of rectal adenocarcinoma with penile metastasis: a case report

BACKGROUND: Despite the rich proximity and vascularization to the pelvic organs, metastatic lesions to the penis are incredibly uncommon. Most primary tumors are genitourinary cancers, and rectal origins are rare. Only 56 cases of metastatic penile tumors have been reported since 1870. Several palliative or curative methods, such as chemotherapy, total penectomy, and radiotherapy, have been applied to treat this condition in previous cases; however, the patient prognosis is poor. Immunotherapy is a beneficial treatment approach for multiple cancers, and recent investigations have shown that it may be beneficial for patients with advanced penile cancer. CASE DESCRIPTION: Herein, we report the case of a 59-year-old Chinese man who had metastatic adenocarcinoma in the penile tissue 3 years after rectal cancer resection. The patient presented with penile pain and dysuria for 6 months when he was 54 years old, and Immunohistochemical staining showed that the origin was the rectum after total penectomy. The patient received surgery, chemotherapy, radiotherapy, targeted therapy and immunotherapy positively and still survived for a further 4 years and 6 months following penectomy despite the late metastasis of rectal cancer. There are two major changes and progress after penectomy, all of which have undergone surgical treatment during continuous treatment and follow-up, the patient completed right inguinal lymphadenectomy when his right regional nodes metastasis was found 23 months after penectomy. While the patient suffered from radiation injury after 47 months after penectomy, which led to radiation necrosis and hip soft tissue infection, and the patient tended to lay prone instead of lying on the back because of the hip pain. The patient ultimately died of multiple organ failure. CONCLUSIONS: All of the previously reported cases of penile metastasis from rectal cancer since 1870 have been reviewed. Yet, the metastatic prognosis remains poor regardless of the treatment options, except for lesions where metastasis is only limited to the penis. We found that the patient may derive more benefit from strategic therapies including surgery, radiotherapy, chemotherapy, targeted therapy, and immunotherapy.