Oral tongue squamous cell carcinoma : assessing treatment outcomes and familial cancer risk

In Studies I and II, we investigated the treatment modalities and outcomes for 360 oral tongue squamous cell carcinoma (OTSCC) patients treated at the five Finnish University hospitals from 2005 to 2009 and compared results with the earlier cohort from 1995 to 1999. Additionally, we assessed the non-curative treatment regimens and survival among 82 OTSCC patients treated at the HUS Helsinki University Hospital from 2005 to 2016. During 2005–2009, OTSCC diagnosis typically occurred at an early stage (78% were clinically T1 or T2 tumors), which undeniably eventuates in better outcomes. The disease recurrence rate for OTSCC patients diagnosed during 2005–2009 was 27%. Overall survival (OS) and disease-specific survival (DSS) rates for patients treated with curative intent were 61% and 76%. Five-year-recurrence-free survival (RFS) for OTSCC has improved from 47% in our previous series to 65% in the current series (P <.001). Regarding patients treated with non-curative intent, survival is decimal (median survival 72 days following the decision of non-curative treatment), and one can consider long the treatment delay (average 19–25 days). For the second part of the research (Studies III and IV), we utilized the Finnish cancer registry (FCR), which includes all new primary cancers diagnosed in Finland since 1953. Study III consisted of 6,602 oral squamous cell carcinoma (OSCC) patients with no previous cancers. We confirmed that OSCC patients carry an 85% excess risk of developing a second primary cancer (SPC) compared with the cancer incidence rates in the Finnish population and the risk persisted even after five years. Patients with a primary tumor in the floor of mouth had the highest standardized incidence ratio (SIR) for SPC (SIR 2.38, 95%-CI: 2.04–2.77, P <.001) when compared to the general population. The respiratory and intrathoracic organs (22% of all SPCs), and digestive organs (21%) were the commonest sites for SPCs. In Study IV, we aimed to elucidate the proportion of HNC cases revealing familial clustering and estimate the relative risk of HNC for family members and spouses of a proband diagnosed with early‐onset HNC. We retrieved from the FCR a total of 923 probands diagnosed with early-onset HNC (≤ 40-year-old) from 1970 to 2012. In this patient cohort, over 97% of HNC cases were sporadic. We detected no increased risk of HNC or other malignancies in first‐ or second‐degree relatives of a proband diagnosed with early‐onset HNC when compared with the general population’s cancer risk. Our study emphasizes that the contribution of shared familial factors, such as inherited genetic mutations, or early HPV‐exposure, to early‐onset HNC, is, in the Finnish population, insignificant and, at most, a minor proportion of early-onset HNC cases is solely attributable to germline mutations.