## 3 Results  
Of the overall population of patients retrospectively reviewed, the amount of which was 5323 ranging from 2016 to 2023, 3925 (74%) were men and 1398 (26%) were women. The median age was 60.59 years (SD \(\pm\) 21.16), 1051 patients were aged \(<\)50 years (19.74%); 1309 were aged 50-59 (24.59%); 1313 were aged 60-69 years (24.67%); and 1650 were aged \(\geq\)70 years (31%).  
The analysis focused on 605 patients discussed in 2019, among whom 28 were selected for the study because they had a lateral cervical mass and uncertainty in diagnosing the primary tumor. The 5-year data analysis showed that nine patients (32%) were classified as having cancer of unknown origin (CUP) because the primary tumor was not identified. For the remaining 19 patients, 10 received a definitive diagnosis of the primary tumor: 3 with localization in the palatine tonsils (one of which was hypercapturing on PET-CT with a size of approximately 7 mm), 2 in the oropharynx, 2 in the nasopharynx, 2 at the base of the tongue, and 1 at the sub-cricoid level in the larynx.  
Of the 28 patients included in the study, 9 (32%) died before the diagnostic course was completed, remaining without a definite diagnosis of the primary site. This evidence highlights the importance of an early diagnostic approach to improve clinical outcomes, especially in patients with an advanced disease presentation.  
The analysis also showed that the male population accounted for the majority of patients involved (74%) and that advanced age was a predominant factor, with 31% of cases among those aged 70 years and older. These data reflect the relevance of multidisciplinary work and the use of advanced techniques to detect the primary tumor and optimize treatment. However, many CUP patients do not reach a diagnosis promptly, highlighting the need for further improvements in diagnostic protocols.  
In the 5-year analysis of individual patients of the 28 from the year 2019 case series (out of a total of 605 subjects), those with an occult tumor revealed the following results (Table 3): 9 patients were classified as CUP since an identifiable tumor could not be found; 10 patients showed, at the end of the examination pathway, a primary tumor, of which 3 had onset from palatine tonsils (of which one identified hypercaptant at PET-CT of about 7 mm); 2 showed localization in the oropharynx; 2 in the nasopharynx; 2 from the base of the tongue; and 1 was laryngeal, found in the sub-cricoid level. The last nine patients died before the diagnostic course necessary to establish the primary localization could be completed, thus remaining without a certain diagnosis of the primary tumor site of onset.  
Figure 1 shows the percentages of patients with certain tumor diagnoses, those with a CUP, and those with a tumor of uncertain origin.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Patients (nr)** & **Primary Tumor** \\ \hline
9 & Classified as unknown primary (CUP) \\
3 & Palatine tonsils \\
2 & Oropharynx \\
2 & Nasopharynx \\
2 & Base of tongue \\
1 & Larynx \\
9 & Not diagnosed (tumor not identified) \\
28 & Total \\ \hline \hline \end{tabular}
\end{table}
Table 3: Diagnosis of tumors in the 28 patients selected.