Abstract 2109
Background
The role of adjuvant therapy has not been clearly defined in certain subroups of salivary gland tumors. Elective LN irradiation has been the subject of debate. Our study analysed various prognostic factors and the role of adjuvant radiotherapy in salivary gland tumors on local control rate and median survival.
Methods
We analysed the data of 84 patients of malignant salivary gland tumors from 2010 to 2015 who underwent primary surgery at out institute with median follow up of 32 months range (3-84 months) using inclusion and exclusion criteria. None of the patients received adjuvant/concurrent chemotherapy in our study. The role of various factors like type of surgery (conservative/radical), grade of tumor, histology, PNI, margin+, LVSI+, adjuvant RT, Elective LN irradiation, LN dissection and size of primary tumor on two year local recurrence rate was evaluated as primary end point. Median survival was our secondary endpoint. Local reactions were evaluated using RTOG criteria. Stastical analysis was done using SPSS version 22.0
Results
Table: 580P
| Gender | MEDIAN- 4O YRS RANGE- 8- 74 YRS |
|---|---|
| Sex | MALE- 38% (n = 32) FEMALES- 72% (n = 52) |
| Site | PAROTID-92.9% (n = 8) SUBMANDIBULAR-4.8 (n = 4) MINOR SALIVARY GLAND-2.4% (n = 2) |
| Surgery | CONSERVATIVE- 81% (n = 68) RADICAL- 19% (n = 16) |
| Histology | MUCOEPIDERMOID- 50% (n = 42) ADENOID CYSTIC CA -16.7% (n = 14) ACNIC CELL CA.- 7.1% (n = 6) SQUAMOUS CELL CA- 4.8% (n = 4) SARCOMA- 4.8% (n = 4) MALGNT. EX PLEOMORPHIC ADENOMA-2.4% (n = 2) |
| LN dissection | 43% (n = 36) |
| pLN+ | 7% (n = 6) |
| Tumor size >4 CMS | 52% (n = 44) |
| GRADE | HIGH-48% (n = 40) INTERMEDIATE-14% (n = 12) LOW-38% (n = 32) |
| LVSI+ | 2.5% (n = 3) |
| Margin+ | 7% (n = 6) |
| PNI+ | 7% (n = 6) |
| Adjuvant RT | 72% (n = 52) |
| Elective LNI | 38%(n = 32) |
| RT dose | MEDIAN- 55 Gy RANGE- 50 -66 Gy |
| 2 yr LC rate | 69% (n = 58) |
| METS+ | 17% (n = 14) |
2 yr local control (LC) in patients who received adj RT is 88.5% and it is 37.5% who didn't receive adj RT which is statistically significant (p 4 cm and LN + have shown a trend to decrease LC rate but are not statistically significant. Interestingly, patients with LN dissection have trend towards decreased LC rate, probably due to more conservative/less aggressive LN dissection in patients who are clinically LN+. Patients with elective LN irradiation (ELNI) have a better 2 yr LC rate in high grade and large tumors than low grade and small tumors (70% vs 41%, p=.04, 64% vs 30%, p = 0.03 respectively). Adj RT doses of more than 60 Gy does not seem to improve LC in adjuvant setting and statistically not significant. The expected median survival in adj RT is 47 months vs 40 months for surgery alone (p = 0.14). Grade II reactions are 79% and 84% for xerostomia and dermatitis.
Conclusions
Adjuvant RT improves local control with trend towards improvement in survival. ELNI in high grade and large tumors is beneficial.
Clinical trial identification
Legal entity responsible for the study
MNJ Institute of Oncology, Hyderabad, India
Funding
None
Disclosure
All authors have declared no conflicts of interest.