Long-term Survival in a Patient with Metastatic Spinal Cord Compression from a Prostate Cancer with Ultra-high PSA: Case Report and Review of the Literature

A 77-year-old man presented to the hospital for non-ambulation of 48 hours prior to admission. He was found to have a metastatic spinal cord compression (MSCC), a PSA exceeding 27,000, and biopsy-confirmed prostate cancer. After palliative radiation (RT) to the spine and medical treatment, the patient recovered his functions fully and survived for more than 7.5 years, far beyond what would be expected based on current published literature. A systematic review of the literature of MSCC in patients with prostate cancer was carried out. Prognostic factors of ambulation after RT included pre-treatment neurological status, duration of neurological deficits, and severity of the neurological impairment. Positive predictive factors of local control included single level of metastasis, time of development of motor deficits of more than 14 days, no prior androgen-deprivation therapy (ADT), age under 65, and longer course of RT (10 fractions of 2 Gy). Absence of prior ADT, pre-treatment ambulation, a single site of metastasis, and haemoglobin of less than 12g/L were positive predictors for survival.


Introduction
Metastatic spinal cord compression (MSCC) occurs in 5-14% of patients with cancer during the course of their disease [1][2]. Although men with MSCC from prostate cancer fare better than patients with other malignancies, prognosis remains poor, with a median survival between 5.4 months and 1.71 year in non-surgical cohorts [3][4][5][6]. Prolonged survival and complete neurologic recovery in patients rendered paraplegic by MSCC is rare, especially in patients who have been paraplegic for longer than 24 hours prior to radiation therapy (RT).
Here is a unique case of a patient with Stage IV prostate adenocarcinoma who presented with diffuse vertebral body metastases and an initial prostate-specific antigen (PSA) in excess of 27,000, who recovered his functionality completely following MSCC and lived for more than seven years thereafter.

Material/methods
The patient provided an informed consent for the publication of his case and his medical records were reviewed.
The English and French-language literature was reviewed according to PRISMA guidelines [7], using 1 2 3 PubMed, Medline, Scopus, and OVID. The search term "prostate" was combined with "adenocarcinoma" or "cancer", and "metastatic", "cord compression", or "spinal tumor". All relevant abstracts and articles were thoroughly examined. Studies were included if they had: 1) patients with a biopsy-proven primary prostate cancer only, 2) documented radiological evidence of spinal cord compression, 3) patients treated with radiotherapy.
Studies were excluded if they 1) included patients with different types of primary cancers (not exclusively prostate cancers), 2) included patients treated surgically for their MSCC, 3) were abstracts or review articles, or 4) did not address patients' outcomes after treatment of the spinal cord compression.

Case Presentation
Mr. GM, a 77-year-old man of Jamaican descent presented to hospital after 48 hours of inability of ambulation, weakness, numbness, and bilateral tingling in his legs. Review of systems revealed only a 14 lb. weight loss over two months. There was no history of trauma, sick contacts, or travels. His past medical history included benign prostatic hypertrophy, chronic kidney disease, and hypertension. His medications included Ramipril and Diclofenac. He was an ex-smoker (10 pack-year history).
On examination, the patient was bedbound. Vital signs were within normal limits (WNL). Neurological examination revealed strength in the lower extremities (LE) of 3+/5 for dorsi-and plantar flexion on the right leg and 4/5 on the left leg. The strength was 3/5 for the hip flexion bilaterally. The strength throughout the upper extremities (UE) was 5/5. Sensation to light touch and pinprick was normal for the UE, but diminished bilaterally in the LE without a clear sensory level. Deep tendon reflexes were 2+ for bilateral UE and knees; ankle jerks could not be elicited. Toes were downgoing on the left and upgoing on the right side. Cranial nerves, II-XII, were normal. The remainder of the examination was non-contributory.
Blood work showed a PSA of 27,394. Chest x-ray demonstrated bilateral pulmonary nodules and a loss of height in the C6-7 and T5 vertebral bodies. A MRI of the spine showed a 6 cm. soft tissue mass at the right lung apex, extending circumferentially and into the spinal canal, resulting in cord compression at T2-T4. There were diffuse bony metastases throughout the spine. A CT-guided biopsy of the lung mass revealed metastatic prostate carcinoma. A prostate biopsy showed prostate adenocarcinoma, Gleason 9 (4+5). Staging abdomino-pelvic CT images showed a large pelvic mass involving the bladder, seminal vesicles, rectosigmoid, and retroperitoneal adenopathy. The bone scan showed diffuse bony metastases.

Treatment
The patient received one dose of dexamethasone 10 mg. IV followed by emergent RT. The radiation was delivered to C7-T5 vertebral bodies and the right upper lung mass with cobalt, using a parallel opposed pair (POP) arrangement. He received 20 Gy in five fractions; dexamethasone, 4 mg QID, that was tapered off. Bicalutamide, 50 mg PO daily (for four weeks), and goserelin, 10.8 mg SQ, were administered; goserelin was continued as trimestrial treatments. One week after initiation of treatments, PSA was 27,300 and three weeks later, it was 9,180.
A few months later, the patient was fully ambulating with a walker and independent for his daily activities. After two years of goserelin, the patient was ambulating without assistance and his PSA was 18. One year later, it rose to 38; CT scan showed progressive hepatic metastases; all the adenopathy had regressed. Bicalutamide, 50 mg PO daily, was initiated, and his PSA decreased to 11. The PSA rose again after a year, and leuprolide was initiated. After not responding to intermittent bicalutamide, this was switched to nilutamide. His disease progressed, and he died 7.62 years after his initial presentation with MSCC.

Discussion
Prostate cancer is the second leading cause of MSCC in men, after lung malignancies. Because patients with prostate cancer may live long enough to develop a recurrence of MSCC, functional recovery, local control (LC) in the treated spinal cord region, and even overall survival are of particular importance in this population.

PSA at presentation and response to treatment
This patient presented with a MSCC and an initial PSA of 27,394, which is, to our knowledge, the highest ever reported PSA level in a patient. Surprisingly, the PSA only decreased to 27,300 after one week of treatment and then to 9,180 three weeks after. This is most likely related to the high dose "Hook effect" [8]. This phenomenon occurs when high concentrations of an analyte give an artifactually lower value when measured by sandwich assays [9]. Vaidya, et al. [8] have advocated the use of a two-step procedure to overcome the effect of excess antigen where unbound excess antigen is washed away before adding the signal antibody to form the sandwich. In fact, this two-step procedure has since been implemented in our institution, but was not routinely performed when this patient first presented.

Review of the literature
This patient had a Tomita score of Grade 3 (i.e., he was non-ambulatory) for 48 hours prior to admission, and his Harrington's classification was Class III [10][11]. Both are significant adverse prognostic factors. Furthermore, a PSA of >40 ng/mL predicts worse outcome [12], which was also the case for our patient. Thus, his functional outcome and longevity were both remarkable given the gravity of his symptoms and his elevated PSA at initial presentation. We have conducted a literature review regarding prognostic factors for ambulation, local control, and survival in patients with prostate cancer who undergo RT for a MSCC. The results of our search are listed in Table 1. Extent of MSCC and anatomic location has no effect.  Factors predicting neurological recovery after RT are summarized in Table 2. Patients with bony compression have worse outcomes than those without bony compression. In Zelefsky's review, the chance of reopening a complete myelographic obstruction associated with a compression fracture was 11% compared to 50% for patients without bony compression (p=0.007) [13].

Positive prognostic factors of ambulation Not prognostic of ambulation
Degree of neurological damage pre-RT RT schedule

RT: radiotherapy
Huddart, et al. also suggested that the time of treatment from the onset of severe neurological deterioration might be more crucial than the time from the first neurological symptoms [4]. Finally, the strongest prognostic factor for functional recovery remains the degree of neurological damage before treatment [6]. Smith, et al. reported that 92% of ambulatory patients, 83% of paraparetic patients, and 20% of paraplegic patients were ambulatory after appropriate treatment [14]. Similar trends were observed in other studies [4,6,15].
Factors associated with improved survival following RT for MSCC are summarized in Table 4. Patients without prior ADT had significantly longer survival than those with prior ADT, with a median survival of 15.5 months compared to six months [4,6]. Pre-treatment ambulatory status and degree of response have also been correlated with improved survival. In Zelefsky's study, the median survival was 9.5 months among patients who obtained a complete response compared to to months for those who did not respond [13].

Positive prognostic factors of prolonged survival Not prognostic of survival
Absence of prior androgen deprivation therapy Gleason score Pre-treatment ambulatory status Total number of metastases Degree of response post-treatment documented by repeat myelography (complete response better than partial response, which is in turn better than no response) Degree of spinal cord compression Single site metastasis Ultra-high level of PSA Haemoglobin >12 g/L PSA: prostate-specific antigen

Conclusions
In summary, sustained function after more than 24 hours of non-ambulation, prolonged LC, and long survival is rare in patients with MSCC. This is even rarer in the context of diffuse bony and vertebral body metastases. Our patient had improvement of function, for more than 7.5 years, after a very poor pre-treatment neurologic status with an initial 48 hours of paraplegia. Although he was hormone naïve, the severity of his clinical presentation, his exceedingly high PSA, age over 75 years, and diffuse vertebral bony metastases, there is no clear explanation for his tremendous functional recovery and long survival, both exceeding far beyond that expected from current published literature. To our knowledge, this is the first documented case of survival of over 7.5 years in a male patient over the age of 75 with widely metastatic prostate adenocarcinoma with a MSCC and a PSA in excess of 27,000.