Abstract
ObjectivesTo define metastatic categories based on their prognostic significance. We hypothesized that oligometastasis in patients with head and neck squamous cell carcinoma (HNSCC) is associated with better post-distant metastasis disease specific survival (post-DM DSS) compared to patients with polymetastasis. Furthermore, the impact on survival of synchronous versus metachronous distant metastasis (DM) occurrence was assessed. Materials and methodsRetrospective cohort study in which patients with DM were stratified into three groups: oligometastasis (maximum of 3 metastatic foci in ≤2 anatomic sites), explosive metastasis (≥4 metastatic foci at one anatomic site) and explosive-disseminating metastasis (spread to ≥3 anatomic sites or >3 metastatic foci in 2 anatomic sites). In addition, patients were divided into synchronous versus metachronous DM. ResultsBetween January 1, 2006 and December 31, 2013, a total of 2687 patients with HNSCC were identified, of which 324 patients developed DM. In this group, 115 (35.5%) patients had oligometastasis, 64 (19.8%) patients had explosive metastasis and 145 (44.8%) patients had explosive-disseminating metastasis. Their median post-DM DSS were 4.7 months, 4.1 months and 1.7 months respectively (p < .001). Synchronous DM was associated with more favorable survival rates in univariable and multivariable analyses than metachronous DM with recurrence of the index tumor (6-month post-DM DSS probability of 0.51 vs 0.17, p < .001). ConclusionOligometastasis in HNSCC signifies a better prognosis than a polymetastatic pattern. Metachronous DM occurrence with recurrence of the primary index tumor is associated with an unfavorable prognosis.
Highlights
Head and neck cancer accounts for more than 850,000 cases worldwide per year [1]
Three patients were excluded due to synchronous non-head and neck squamous cell carcinomas (HNSCC) at the time of Distant metastasis (DM), two patients were excluded due to non-HNSCC related cause of death, another two patients were excluded due to missing records and one patient was excluded as DM was found at post-mortem examination
This study demonstrated that an oligometastatic pattern is associated with more favorable survival rates compared to an explosivedisseminating pattern
Summary
Head and neck cancer accounts for more than 850,000 cases worldwide per year [1]. The vast majority of these cases are squamous cell carcinomas (SCC). Substantial heterogeneity appears to exist in survival between patients with DM i.e. patients with fewer metastatic foci seem to have better overall survival (OS) rates in comparison to patients with polymetastasis [7,8]. This is in line with the concept of “oligometastasis” (OM) proposed by Hellman and Weichselbaum in 1995 [9]. This concept suggests that metastasis should not be regarded as a binary state (metastases either do or do not exist), but rather as a spectrum of metastatic disease. In head and neck squamous cell carcinomas (HNSCC), it remains undefined as to what number of metastatic foci and locations constitute OM
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