(P 285) IMPACT OF ACRIDINE ORANGE IN PATIENTS WITH LOCAL RECURRENT SOFT TISSUE SARCOMA

Objective: Although radical resection with adequate margin is important in the treatment of soft tissue sarcoma (STS) for the prevention of local recurrence, it is difficult to excise a tumor in contact with important tissue while maintaining a sufficient margin. If resection is conducted in the area where the tumor is in contact with the tissue, the recurrence rate increases. Local recurrence in STS is a risk factor of worse prognosis, and once local recurrence occurs, it is more difficult to control the STS. Acridine orange (AO) is accumulated in acidic environments, and AO specifically binds to malignant tumors and immediately accumulates in tumor cells after local administration. AO has a strong cell destruction effect on tumor cells after a single session of blue light excitation or low-dose radiation, and residual tumor cells after tumor resection are killed. Although a few studies showed that adjuvant therapy with AO was effective for local control of primary STS, there have been no reports examining its effectiveness for local recurrence. We compared the control efficacy on local recurrence in STS between a marginal excision with adjuvant AO therapy and a wide excision.

Methods: This retrospective study included 36 patients with first local recurrence of STS, with a mean age of 66.9 years. Of them, 23 patients received wide excision without AO therapy (Wide group); the other 13 patients received marginal excision with AO therapy (AO group). Marginal excision with AO therapy was performed on patients when the recurrent tumor was contacting major nerves or vessels, bones, and/or major organs without any signs of massive invasion upon pre-surgery image evaluation. They had not developed distant metastases prior to the surgery for the local recurrence. The patients’ information, including age, sex, histological diagnosis of the tumor, anatomical location of the tumor, primary and recurrence tumor sizes, histological grade, stage of the primary tumor, treatments for the primary and recurrence tumors, local re-recurrence, distant relapse, time to the local recurrence, follow-up period, and outcomes, was collected. We compared re-recurrent rates between these two groups and analyzed factors for re-recurrence and prognosis after the first recurrence.

Results: The total re-recurrence rate was 43.5% in the Wide group and 46.2% in the AO group. There were no significant differences in clinical information between the Wide group and the AO group. There was no significant difference in Kaplan-Meier curves for local re-recurrence-free survival and overall survival between the two groups. In the univariate logistic analysis, which investigated factors associated with the local re-recurrence, only being male was identified as a risk factor for local re-recurrence (p< 0.05). In multivariate analysis, the size of the recurrent tumors and metastasis after surgery for the recurrent tumor were identified as risk factors for poor prognosis (both p< 0.05).

Conclusion: The inhibitory effect of a marginal excision with adjuvant AO therapy on local re-recurrence of local recurrent STS is just as efficacious as a wide excision. The size of recurrent tumors and distant metastasis after surgery for recurrent lesions correlate with worse prognoses.





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