head and neck rhabdomyosarcoma; clinicopathological features, trends, and role of adjuvant therapy.
Purpose/Objective
Rhabdomyosarcoma is an aggressive tumor that arises from the muscles and carries poor prognosis. Although it is the most common head and neck sarcoma, it is considered rare. This scarcity has led to a lack of information about its features. Therefore, we aim to assess its clinicopathological features and trends as well as define the role of adjuvant therapy.
Material/Methods
We identified 618 patients with head and neck rhabdomyosarcoma from the Surveillance, Epidemiological, and End Results (SEER) database diagnosed from 2000-2020. We analyzed Age-Adjusted Trends and incidence rates. Rates are per 100,000 and age-adjusted to the 2000 US Std Population (19 age groups - Census P25-1130) standard; Confidence intervals are 95% for rates (Tiwari mod) and trends. Percent change was calculated using 1 year for each end point; APC was calculated using weighted least squares method. Kaplan-Meier curve and Log rank test were done using SPSS 25 to perform survival analysis. Cox regression hazard model was also calculated to identify predictors for outcome.
Results
The incidence rate of Head and Neck Rhabdomyosarcoma was 4%. Age-adjusted trend analysis showed a percent change (PC) of 18.9 and an annual percent change (APC) of 0.06 (95% CI: -1.12 to 1.25). Age group under 20 years showed the highest incidence rate of 5.5% however, it showed a decrease in its incidence rate compared in 2000 by 23% where it was 7.2%. Age groups 20-49 and 50+ showed slightly lower incidence rates of 4% but there has been a rise in their incidence of 54% and 91% respectively (2.6% and 2.1% in year 2000).
Males showed higher incidence rate; 5.6%, compared to females; 3.4% but both showed an increase in their incidence rates in year 2020 compared to year 2000; PC= 18% and 21% respectively. White race showed a 30% increase in its incidence rate from 2000 to 2020 to be 4.9% and Asian demonstrated only a 7% rise in its incidence to be 3.4%. For black, incidence rate decreased by 25% to be 4.2% in 2020 compared to 5.6% in 2000.
The 5-year relative survival was 46.1% (P<0.05). Surgery and radiotherapy showed to improve survival with hazard ratios (HR) of 0.73 and 0.74 respectively; P<0.05. Increasing age was associated with poorer outcomes; HR of 1.03; P<0.05. Sex, race, laterality and chemotherapy were not significant predictors for outcomes; P>0.05.
Conclusion
Head and neck rhabdomyosarcoma showed an incidence rate of 4%. Although it is considered a low incidence rate for a type of cancer, it is classified as a prevalent type compared to sarcomas which are considered rare tumors. There has been rising incident rates among all genders. For age group under 20, despite its declining incidence rates, it remains higher than other age groups. Other age groups are showing rising incidence rates. White and Asians are showing increasing rates while Black incidence rates are decreasing. Rhabdomyosarcoma are increasing in incidence rates among most of the population and so we recommend the implementation screening methods.
Head and neck rhabdomyosarcoma also showed poor survival outcomes. Patients who undergone surgery or had radiotherapy were 25% less likely to face poor outcomes so, we recommend them as treatment options of good prognostic value. Increasing age was associated with poorer prognosis. Sex, race, laterality and chemotherapy didn’t affect prognosis. We can avoid the unfavorable side effects of chemotherapy as it wasn’t found to impact outcome.
