Soft tissue sarcomas in the first year of life

Soft tissue sarcomas (STS) occurring in the first year of life represent a rare entity. Challenges in delivering optimal therapy may affect the outcome in this very young population.

We searched the SEER database for records of infants less than 1 year of age, with a reported diagnosis of STS who were diagnosed from 1973 to 2006. We analysed their clinical features and survival. These patients were also compared to older patients (1-18 years old) in order to understand the differences between the two groups.

The incidence rate of STS in the first year of life was 16.0 per million. As an entity, they represented 7.3% of malignancies reported in the first year of life. One fifth of these tumours (20.9%) were reported to be metastatic at diagnosis. The most common histologies were rhabdomyosarcoma (n=99, 32.8%), fibrosarcoma (n=74, 24.5%), malignant rhabdoid tumours (n=43, 14.2%) and haemangiopericytoma (n=12, 4.0%); except for rhabdomyosarcoma, the other 3 entities were very rare in older children. The 5-year survival of STS in children less than 1 year of age (62+/-3.0%) was significantly worse than that of older children (71+/-0.9%, P=0.0002). In a multivariate model, histologic types other than fibrosarcoma and haemangiopericytoma (HR, 5.7; 95% CI, 2.28-14.20) as well as advanced stage (HR, 5.15; 95% CI, 3.28-8.10) were found to be significant adverse prognostic factors. Significantly less use of radiation was reported in infants when compared to older children (P<0.0001).

As a group, infantile STS are associated with worse survival than STS in older children. Outcome, however, is significantly associated with histologic subtype, with infantile fibrosarcoma and infantile haemangiopericytoma having better outcomes. Avoidance of radiotherapy in this young age may contribute to worse outcomes.