Our study evaluated whether dental treatment before OOPSCC therapy alters existing systemic comorbidities. The results suggested that although OOPSCC patients have comorbidities and several abnormal laboratory tests results, the dental treatment in these cancer populations resulted in no adverse events. It was also observed that the OOPSCC diagnosis does not pose an additional challenge for the dentist, as treatment complications such as unexpected bleeding or infection were not identified in the population evaluated.
It is recommended that OOPSCC patients should receive comprehensive oral assessment and dental treatment before cancer treatment. It ought to start right after the cancer diagnosis. When an oral/dental surgical procedure such dental extractions is indicated, ideally it should be concluded 2–3 weeks before the start of the cancer treatment to allow time for bone and soft tissue healing [2–4, 24].
We used comorbidity to refer to disease processes that coexist and are not related to the index disease being studied [25]. Current literature highlights that the frequency of comorbidities in OOPSCC patients is high compared to the general population, and it is mainly associated with chronic smoking and alcohol exposure [26,27]. A review demonstrated that approximately 60% of H&N cancer patients have concurrent illnesses [25]. Our study, which originally assessed a Latin American population with advanced OOPSCC, observed that 85.4% of patients had a history of tobacco/alcohol consumption. In addition, patients reported an overall comorbidity rate of 63.6% (44.3% one, while 55.7% with two or more concurrent).
The most common comorbidities reported were hypertension (51.4%), followed by dyslipidemia (22.8%) and diabetes (15.7%). This is similar to the results of a study population of 10,524 H&N cancer patients (3049 diagnosed with oral and 2499 diagnosed with oropharyngeal cancer), with the most reported comorbidities being hypertension (59.6%), hyperlipidemia (31.4%), chronic obstructive pulmonary disease (COPD; 26.4%), and diabetes (21.1%) [29]. Comorbidities can impact the diagnosis, prognosis, survival and treatment of patients with cancer and dictates the cancer treatment modality and shapes the way dental treatment is provided [28,29].
The most frequent altered laboratory findings were elevated CRP, altered levels of hemoglobin, erythrocytes, hematocrit, GGT, 25-Hydroxy Vitamin D, RDW-SD, neutrophil counts, eosinophil counts, total cholesterol, HDL, iron, and glucose. A retrospective study of 261 H&N cancer patients that evaluated pre-therapeutic laboratory values also demonstrated that elevated CRP were the most frequent laboratory anomaly (60%), but they also observed impaired liver enzymes (30–50%), leukocytosis (20%), and anemia (10%) [30].
The results of our study suggest that the observed comorbidities do not require dental treatment modifications and do not generate complications related to invasive dental procedures. CRP is a nonspecific inflammation marker synthesized in response to acute inflammation or destruction of tissue cells and over-expressed levels are demonstrated to be prognostic markers in various tumors, including lung, lymphoma, and more recently, H&N cancers [31,32]. Altered liver function GGT can be explained by the chronic alcohol abuse in this population [30]. 25-Hydroxy Vitamin D monitors vitamin D levels, and deficiency is highly prevalent among adults, and low levels have been associated with hypertension, cancer, and diabetes mellitus [33,34]. Neutrophils, the most abundant leukocytes in the blood, are considered to be the first line of defense during inflammation and infections. High counts in the H&N cancer population are associated with poor cancer prognosis. Low counts are associated with infection [35,36]. The high incidence of altered blood glucose concentration is associated with the high number of diabetic patients in this targeted sample.
The current literature suggests that general dentists may have limited experience in the care of the cancer patient. Professionals with experience in oral oncology are usually the ones who diagnose and manage oral conditions and diseases in OOPSCC patients [24]. While this may be true for patients already undergoing or that have already concluded cancer treatment, our study suggests that routine dental treatment before OOPSCC may be performed by general dentists. Although comorbidities and laboratory changes were observed in our study population, they did not generate relevant treatment complications that contraindicated dental treatment.
H&N cancer treatment toxicities are frequent, affect patients' QoL, may cause treatment breaks, and eventually impair prognosis [3–4]. In our study, toxicities were progressive over time and independent of the chosen RT modality. There was a positive correlation between the number of medications in use and OM and a negative correlation between the number of medications in use and dysgeusia outcomes.
To our knowledge, this is the first study to correlate the presence of comorbidities, laboratory changes and toxicities from the curative treatment (RT or CRT) in OOPSCC patients, and the provision of routine dental care before the start of cancer therapy. Because the findings of this study are unique, there is no existing literature to support or to compare our results.
Nevertheless, some findings in the present study may be considered predictive of oral toxicities during oncological treatment. We demonstrated that urea levels were altered at D25/30/D33-35 and creatinine at D15/30 of RT or CRT treatment, pointing to altered renal function and impairment of drug metabolism in patients undergoing these treatment modalities. Ultimately, this could imply more severe mucositis [37]. Additionally, we observed that altered T4 and FT4 levels were correlated with OM. T4 altered levels and OM were seen in D20/25, and slightly less in D30/33–35. Correlation between OM and FT4 is only significant at D33-35, but also showed a trend at D20/25/30.
A syphilis diagnosis was correlated with OM at D15, and OC was associated with syphilis and HIV diagnosis at D20 of the RT treatment. The baseline immunosuppression added to the cancer-treatment related immunosuppression might favor this scenario [38].
Of interest, we observed that both family income and housing were the most important predicting factors for OM. These predictors could be explained based on the sociodemographic context of OOPSCC patients in Brazil - a low income and low education level can affect compliance and follow-up of recommendations which could worsen OM grades [39].
Limitations of the present study include the short follow-up time after diagnosis and treatment. Because of this, it was not possible to directly correlate abnormal laboratory test values and the OOPSCC prognosis and cancer treatment outcomes. The heterogenic population that participated in the study, the different treatment modalities used to treat the patients, and some of the correlations observed are also limitations to be considered in this study.
The mean OHIP-14 score from the study population was 19.5, and the worst domain reported was physical pain (4.37). These findings are similar to a study also conducted in Brazil with H&N cancer patients, in which the mean score obtained was 19.52 (± 11.79) and the physical pain (3.70 ± 2.44). These two findings ranked as the main factor affecting QoL [40].