The role of site-specific therapy for cancers of unknown of primary: A meta-analysis

Cancers of unknown primary (CUP) are among the most common causes of death due to cancer, are associated with a poor prognosis and have few therapeutic options available. Molecularly-guided site-specific treatments were explored based on the assumption that CUP are similar in their response to treatment of predicted primary tumours. Given the discordant results between these studies, a meta-analysis using a random-effects model and the inverse variance method was performed. MEDLINE and conference abstracts of American Society of Clinical Oncology (ASCO) and European Society of Medical Oncology (ESMO) meetings were searched from inception until November 2019. A trend towards improved OS was noted with site-specific versus empiric treatment for CUP (HR = 0.73; 95% confidence interval (CI) 0.52–1.02). There was significant heterogeneity across the four studies (I [2] = 79%; p = 0.002) but no significant difference was noted between the treatment effect in the two subgroups (randomised vs. non-randomised; p = 0.07). The test for overall effect for progression free survival, which had only been reported for the two randomised studies, was not statistically significant (HR = 0.93; 95% CI 0.74–1.17), with little heterogeneity between studies (I [2] = 0%; p = 0.77). The results of this meta-analysis highlight the significant heterogeneity between the prospective studies comparing molecularly tailored to empiric therapy for CUP and the need for other randomised studies including only primary tumors with available effective therapies.