The molecular basis for the clinical behavior remains unknown.
The expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and mammalian target of rapamycin (mTOR) were detected immunohistochemically in 40 sacral chordoma tissues and 10 adjacent normal tissues. Correlations between PTEN and mTOR expression and clinicopathological factors were analyzed. Kaplan-Meier survival curves and log-rank test were used to analyze the continuous disease-free survival time (CDFS). The expression of PTEN in sacral chordoma was significantly lower than that in adjacent normal tissues, while the levels of mTOR expression in sacral chordoma were significantly higher than that in adjacent normal tissues (P = 0.000, P = 0.030). The positive expression of mTOR appears to correlate with the negative expression of PTEN in sacral chordoma (P = 0.021). PTEN-negative expression and mTOR-positive expression were associated with tumor invasion into the surrounding muscles (P = 0.038, P = 0.014). Log-rank test showed that PTEN-negative and mTOR-positive expressions had an important impact on the patients’ CDFS (P = 0.011, P = 0.015).
Results suggest that PTEN and mTOR might play an important role in the local invasiveness of sacral chordoma. PTEN and mTOR might be recognized as important prognostic predictors of recurrence and could be used as potential therapeutic targets for the treatment for sacral chordoma 2).
May produce pain, sphincter disturbance or nerve root symptoms from local nerve root compression. It may occasionally extend cephalad into the lumbar spinal canal. It is usually confined anteriorly by the presacral fascia, and only rarely invades the wall of the rectum 3).
A firm fixed mass may be palpable between the rectum and the sacrum on rectal exam.
Characteristic radiographic findings: centrally located destruction of several sacral segments, with an anterior soft-tissue mass that occasionally has small calcifications. CT and MRI show the bony destruction. This is usually difficult to see on plain x-rays. MRI also shows the soft-tissue mass.
Open or CT guided percutaneous posterior biopsy can confirm the diagnosis. Transrectal biopsy should be avoided because of the potential of rectal spread of tumor 4).
Chest CT and bone scan: to R/O mets for staging purposes.
The particulars of the surgical procedure are highly dependent on the extent of the lesion. These tumors may spread through the gluteal musculature, and if significant muscular excision is required, then a pedicle based rectus abdominis flap may be employed. A diverting colostomy may be required if it is necessary to resect the rectum or if a cephalic sacral resection is anticipated.
For chordomas caudal to the third sacral segment, most agree that a posterior approach is satis- factory. For more rostral lesions, some advocate a combined anterior-posterior approach. However, a posterior approach has been also been used for these.
Adverse effects of sacrectomy: if S2 nerve roots are the most caudal nerve roots spared, there is ≈ 50%chance of normal bladder and bowel control. If S1 or more cephalic roots are the most cau- dad nerve roots spared, most will have impaired bladder control and bowel problems. 5).
Best results were obtained with en bloc excision (even if marginal), sometimes combined with high- dose XRT 6) 7) , (conventional XRT did not prevent recurrence when incorporated with palliative or debulking surgery 8) , but it did lengthen the interval to recurrence). Early radiation was associated with longer survival 9). Higher XRT doses can be used in the sacrococcygeal region (4500–8000 rads) than in the cervical spine (4500–5500 rads) because of concerns of radiation injury to the spinal cord. IMRT and stereotactic radiosurgery have also been used 10).
Proton beam therapy 11) , alone or combined with high-energy x-ray (photon) therapy 12) 13). may be more efective than conventional XRT alone. However, proton beam therapy requires travel to one of a very limited number of facilities with a cyclotron (in the U.S.: Boston, or Loma Linda, California) which may be di cult to arrange for what is typically ≈ 7 weeks of fractionated treatments.
The presence of subcutaneous fat extension was an independent predictor of decreased OS. Other MRI findings with potential for future evaluation include size, presence of soft tissue tail, extension above L5/S1, and SI joint and piriformis muscle invasion 15).
Dedifferentiated chordomas are aggressive malignant tumors with a higher risk of local recurrence, metastases, and early mortality than conventional chordomas. Tumor diameter >10 cm, marginal resection, and sacroiliac joint infiltration may be associated with increased risk of local recurrence and mortality. Those with a smaller burden of dedifferentiated disease (<1 cm) within the primary chordoma have a better prognosis. Patients should be counseled about these risks before surgery and should have regular follow-up for the detection of local recurrence and metastases 16).
A total of 41 patients underwent en bloc resection of sacral chordoma with preoperative MRI scans. Tumor characteristics included lobulated: (93%) and soft tissue tail (54%). The following areas had tumor invasion lobulated: sacroiliac (SI) joint (15%), ilium (5%), piriformis (61%), gluteus (46%), subcutaneous fat (32%), and lumbosacral venous plexus (22%). After multivariable analysis, only subcutaneous fat extension was an independent predictor of decreased OS (hazard ratio 5.30, 95% confidence interval 1.47-19.19, P = .011). Though not significant after multivariable analysis, the following factors were significant predictors of LR after univariate logrank testing: above the L5/S1 disc space (P = .004), SI joint invasion (P = .036), and piriformis extension (P = .022).
The presence of subcutaneous fat extension was an independent predictor of decreased OS. Other MRI findings with potential for future evaluation include size, presence of soft tissue tail, extension above L5/S1, and SI joint and piriformis invasion 17).