The data of 175 patients irradiated for MSCC from cancer of unknown primary between 1991 and 2011 were retrospectively reviewed. The patients had to fulfill the following criteria to be included in this analysis: motor deficits of the lower extremities caused by metastatic compression of the thoracic or lumbar spinal cord, confirmation of the diagnosis with spinal computed tomography or magnet resonance imaging, and no previous surgery or radiotherapy within the involved parts of the spinal cord. The patients were given a daily dexamethasone dose between 3x4 mg and 4x8 mg from the first day of radiotherapy and then at least for another week. The patients were generally presented to a neurosurgeon or an orthopedic surgeon to discuss whether upfront decompressive surgery may be a reasonable option or not. Patients were generally not considered for surgery if they had a poor performance status (ECOG 3–4), involvement of several spinal sites, severe neurologic deficits (paraplegia) for longer than 48 hours, and a poor expected survival in case of multiple extraosseous lesions. Only 10% of the patients who presented with MSCC from CUP were considered candidates for surgery. The data were collected from the patients themselves, their files, and their general practitioners or treating oncologists. Because this study did not report on a clinical trial, and because the data were retrospective in nature and analyzed anonymously, approval by an ethic committee was not necessary. The patient characteristics are summarized in Table .
Every participating center contributed an unselected series of patients with MSCC treated within a specific time period. The energy used for irradiation varied between 6–10
MeV photons, and the planning target volume included one uninvolved vertebra above and below the metastatic lesions. Motor function was assessed right before the start of radiotherapy, as well as at one month, three months and six months after radiotherapy was completed. To categorize motor function we used a 5-point scale: Grade 0: normal strength; Grade 1: ambulatory without aid, Grade 2: ambulatory with aid, Grade 3: not ambulatory, Grade 4: paraplegia [10
]. If the patient’s motor function was rated as improved or deteriorated, an alteration of at least one point on the 5-point scale must have had occurred. Patients who presented with complete paraplegia and did not approve were rated as deteriorated.
The following nine potential prognostic factors were investigated with respect to post-radiotherapy motor function, local control of MSCC, and survival: age (≤65 vs.
years), gender, Eastern Cooperative Oncology Group performance score (ECOG-PS 2 vs.
3–4), number of involved vertebrae (1–2 vs.
3), pre-radiotherapy ambulatory status (not ambulatory vs.
ambulatory), other bone metastases at the time of radiotherapy (no vs.
yes), visceral metastases at the time of radiotherapy (no vs.
yes), time developing motor deficits before radiotherapy (1–7 vs.
days), and the radiotherapy schedule (short-course radiotherapy with 1x8 Gy or 5x4 Gy in 1
longer-course radiotherapy with 10x3 Gy in 2
Gy in 3
weeks, or 20x2 Gy in 4
The nine potential prognostic factors for functional outcome were included in a multivariate analysis performed with the ordered-logit model, because these data were ordinal (−1
no change, 1
improvement of motor function). Local control was defined as no recurrence or progression of MSCC in the irradiated spinal region. The diagnosis of an in-field recurrence of MSCC was confirmed by computed tomography or magnet resonance imaging. Local control and survival rates were calculated with the Kaplan-Meier-method [11
]. The differences between the Kaplan-Meier curves were calculated with the log-rank test. The prognostic factors found to be significant (p
0.05) in the univariate analysis were included in a multivariate analysis, performed with the Cox proportion hazards model. Patients were followed until death or for median 7.5
months (range: 6–20
months) in those alive at the last follow-up visit.