The present findings demonstrate an epidemiological profile characterized by black and brown men over 60 years of age with low income and low educational attainment and without formal education, in agreement with the literature [11, 14, 15–17]. As reported in other studies, most patients had a low income and low educational attainment and no formal education [6, 10, 18–19]. The present study reports the profile of oral cancer in a northeastern state of Brazil, which does not differ from the rest of the country [13, 19–20].
Regarding behavioral factors, most patients were smokers and alcohol drinkers and this pattern persisted throughout the series. These findings are similar to the majority of studies found in the literature [5, 7, 10–11, 14, 16–17]. Although the epidemiology of oral cancer, and especially of oropharyngeal cancer, has changed in recent years, with an increase in cases of cancer related to human papillomavirus [21–27], tobacco and alcohol are still the main factors responsible for cancer initiation and promotion [23, 28].
Conventional squamous cell carcinoma is the most common histological type diagnosed in the oral cavity [7, 16, 29]. The tongue was the most frequently affected site (⅔ anterior), similar to the majority of studies [11, 13–14, 17, 20, 25, 29–31]. Most patients had stage III and IV cancer at the time of diagnosis, in agreement with the literature that states that cases of oral and oropharyngeal cases are predominantly diagnosed late [1, 11, 14, 17, 20, 25, 29, 31–35].
Metastasis to the submandibular, submental and cervical lymph nodes worsens the tumor stage and, consequently, patient survival. Assessment of metastasis is decisive for staging and for the choice of treatment [1, 33]. Lymph node metastasis was a risk factor for death (15 times higher risk), as was worse disease progression with a 2.25-fold effect on disease-specific survival at 3 years.
The mean interval in days between the patient noticing the lesion and seeking care is still long (241 days). The mean disease-specific survival time was 6.73 ± 5.81 months in patients who died. Patient delay has been reported in the literature to be responsible for the longest delays [11, 29, 34], in agreement with the study by França et al. [35] who found that a longer interval between diagnosis and the initiation of treatment is a risk factor associated with poor overall survival.
Late treatment may be the result of the lack of health education and early diagnosis [28, 33]. The delay in scheduling a consultation might be due to health system barriers, limited resources, and broad health economic issues [1, 18, 30, 34, 36–38]. A delay between the first consultation and the diagnosis of oral cancer can be considered a risk factor linked to the stage of the disease. Within this context, early diagnosis has been suggested as another important prognostic factor of overall survival since survival rates exceeded 80% in patients diagnosed with oral cancer and treated in early stages (I and II), while those diagnosed in advanced stages (III and IV) had 5-year survival rates ranging from 20 to 50% [26, 38–41].
In 2012, Brazil sanctioned the law that establishes a maximum period of 60 days between the diagnosis of a malignant neoplasm and the first cancer treatment, in addition to the amendment of law 13,896, of 10/30/2019, which establishes a period of 30 days (4 weeks) for performing tests related to the diagnosis of malignant neoplasms [35, 39, 40]. These intervals are similar to those reported by the Brazilian Ministry of Health in its Oncology Panel, which found for the year 2018 that 45% of lip and oral cavity cancer cases were treated within an interval of more than 60 days. The highest percentages of cases treated more than 60 days after diagnosis were found in the northern and northeastern regions [30, 35, 41–42]. According to data from the Hospital Cancer Registry (Integrador RHC) of the Brazilian National Cancer Institute (INCA) for the period from 2017 to 2019, the average interval between diagnosis and the initial consultation was 62.5 days in 2017, 43 days in 2018, and 58 days in 2019; the average interval between diagnosis and the initiation of treatment was 118.3 days in 2017, 71.3 days in 2018, and 66.7 days in 2019. Comparing the findings of the present study with the INCA Integrador RHC data shows a better scenario for the latter [42].
According to treatment guidelines for head and neck cancer, surgery is recommended for the treatment of T1 and T2 oral cavity tumors. In the case of more advanced tumors (T3 and T4), there is concern about the surgical indication because of the anatomical and functional changes caused by surgery. Neck dissection is recommended in the case of lymph node involvement (N1 to N3), or for N0 patients with high-risk criteria (floor of the mouth tumors measuring more than 2 cm in length or 4 mm in thickness). Radiotherapy is reserved for cases in which surgery may lead to potential functional loss. Radical surgery with unilateral or bilateral neck dissection followed by radiotherapy or adjuvant chemoradiotherapy is indicated for locally advanced resectable disease (T3 or T4a) [33]. In oropharyngeal cancer, both surgery and radiotherapy provide similar conditions for the regional control of T1-T2 tumors. In cases of locally advanced resectable disease (T3 or T4a), a combination of surgery and radiotherapy or chemoradiotherapy may be performed. Unresectable tumors of the oral cavity and oropharynx can be managed by concomitant chemotherapy and radiotherapy or chemotherapy prior to radiotherapy [33].
Slightly more than half of all patients (52.2%) underwent surgical treatment alone or in combination. Patients submitted to surgery, especially those with T1 and T2 tumors, had a longer disease-specific survival time. Data from the Hospital Cancer Registry (Integrador RHC) of INCA [41] show that surgical treatment accounted for 38.3% of all treatment modalities between 2017 and 2019. There was an increase in the percentage of patients treated by surgery over the years; however, an increase was also observed in the percentage of untreated patients, which increased from 6.3% in 2017 to 12.3% in 2019.
Analysis of the time series also showed an expressive percentage of deaths. Half of the patients had already died by the end of the series. A study that analyzed data from the same region also found low survival of patients with oral and oropharyngeal cancer in a retrospective cohort of cases covering the period from 2005 to 2013 [16]. One study found that the mortality rate due to oral and oropharyngeal cancer was 3.94 times higher in men than in women. The three sites accounting for the highest percentage of deaths were the oropharynx (31.72%), other and unspecified parts of the mouth (21.55%), and other and unspecified parts of the tongue (18.95%) [9]. These findings again highlight the need for public policies that ensure surveillance of new cancer cases, access of the most vulnerable population, and health education to improve early diagnosis [7–8, 26, 37, 43].
In the present study, patients who had a consultation in 2017 had a 3.57 times higher risk of being dead compared to the reference year, which was 2020. The risk of being dead was 3.04 times higher for patients who had the first consultation in 2018 compared to the reference year and 3.14 times higher for those who had the first consultation in 2019. This finding reinforces evidence showing that there has been no improvement in the survival of patients with oral cancer in recent decades nor a decrease in the number of deaths. These results are most likely due to late care seeking [7–8, 26, 31, 37, 43–44].
Among the cancer-related factors, patients with positive lymph nodes had a significantly higher risk of death (p = 0.02) and shorter disease-specific survival. Patients with smaller tumors (T1 or T2) had a significantly lower risk of death (p < 0.001) than those with larger tumors (≥ T3), as well as longer disease-specific survival.
According to the results of studies, the identification of tumors at an early stage in primary care and the referral of these patients to specialized oral health centers contribute to increasing the rate of resolution of cases and to reducing the demand of patients in an advanced stage for hospital services [21, 41].