The duration, in months, between the initiation of any relevant prior treatment (e.g., symptomatic management, imaging, or biopsy) and the date of histopathological diagnosis of sacral tumor

Calculated as weight in kilograms divided by height in meters squared (kg/m²), recorded as a continuous variable.

Documentation of any tumor-related treatments received prior to surgery, including radiotherapy, chemotherapy, embolization, or prior surgical interventions.

Patient performance status at the time of enrollment, scored using the Eastern Cooperative Oncology Group (ECOG) scale (range: 0 to 5), where higher scores indicate worse functional impairment.

The secondary outcome measure will assess rectal function 12 months after sacral tumor resection surgery. Based on the Biagini et al. method and supported by literature such as Huang et al the Bowel function scoring system commonly used in sacrectomy outcome studies includes the following components:

0-Normal

1. Feels stimulus to defecate and is incontinent when feces are soft or under stress
2. Does not feel stimulus to defecate and/or is completely incontinent

Based on the Biagini et al. method and supported by literature such as Huang et al the bladder function scoring system commonly used in sacrectomy outcome studies includes the following components:

0-Normal

1. Feels stimulus to micturate and has limited continence at varying times and quantities of urine and/or has increasing postmicturition vesical residual and/or urinary loss in conditions of stress
2. Does not feel stimulus to micturate and/or is completely incontinent

This outcome measure will assess pain levels prior to surgery using the Visual Analog Scale (VAS). The VAS is a widely used tool for measuring the intensity of pain, with patients indicating their level of pain on a scale from 0 (no pain) to 10 (worst possible pain). This pre-surgical pain assessment will provide a baseline for understanding the patient's pain levels, which will be compared to post-surgical pain levels to assess recovery and the effectiveness of post-operative pain management.

Total duration of the surgical procedure, measured in minutes from initial incision to closure.

Estimated total volume of intraoperative blood loss, recorded in milliliters (mL).

The operative corridor used to access the tumor, classified as anterior, posterior, or combined anterior-posterior approach.

Whether spinal or pelvic instrumentation (e.g., screws, rods) was implanted during surgery (yes or no).

The most cephalad sacral vertebral level at which osteotomy was performed, based on intraoperative and radiographic records (e.g., S1, S2, S3, etc.).

The number and laterality (unilateral/bilateral) of sacral nerve roots ligated or sacrificed during tumor resection, documented per operative report.

Type of surgical excision performed, categorized as en bloc resection or piecemeal resection.

Whether the tumor showed direct involvement or adherence to the bowel, as identified during surgery (yes or no).

Presence of tumor adhesion to major pelvic vessels observed intraoperatively, as judged by the operating surgeon (yes or no).

The secondary outcome measure will assess rectal function 12 months after sacral tumor resection surgery. Based on the Biagini et al. method and supported by literature such as Huang et al the Bowel function scoring system commonly used in sacrectomy outcome studies includes the following components:

0-Normal

1. Feels stimulus to defecate and is incontinent when feces are soft or under stress
2. Does not feel stimulus to defecate and/or is completely incontinent

Based on the Biagini et al. method and supported by literature such as Huang et al the bladder function scoring system commonly used in sacrectomy outcome studies includes the following components:

0-Normal

1. Feels stimulus to micturate and has limited continence at varying times and quantities of urine and/or has increasing postmicturition vesical residual and/or urinary loss in conditions of stress
2. Does not feel stimulus to micturate and/or is completely incontinent

Postoperative pain intensity is assessed using the Visual Analog Scale (VAS), ranging from 0 (no pain) to 10 (worst imaginable pain). Patients are asked to report their daily worst pain. All patients receive standardized NSAID treatment. If additional opioid analgesics are used, the VAS score prior to opioid administration and the dose of opioid used are recorded. Higher scores indicate more severe pain

Health-related quality of life is evaluated using the EORTC QLQ-C30 questionnaire, a validated 30-item instrument developed by the European Organisation for Research and Treatment of Cancer. It includes five functional domains, three symptom domains, a global health status score, and additional symptom items. Scores range from 0 to 100. For functional and global health domains, higher scores indicate better function; for symptom domains, higher scores indicate more severe symptoms.

Defined as the time interval from the date of surgery to the date of radiologically or clinically confirmed tumor progression or recurrence, as assessed by postoperative MRI and/or symptom evaluation. Patients without progression at the time of last follow-up will be censored.

Defined as the time from surgery to death from any cause. Patients alive at the time of last follow-up will be censored.

Documentation of any postoperative oncologic therapy, including radiotherapy, chemotherapy, targeted therapy, or immunotherapy. Treatment modality, agent used, and combination strategy (if any) are recorded.

Duration of each adjuvant therapy regimen (in days), recorded from initiation to completion or discontinuation. Reasons for discontinuation, if applicable (e.g., toxicity, progression), are documented.