Colorectal cancer in patients under age 50 : a five-year experience

Objective: to evaluate the clinical characteristics of patients with colorectal cancer under the age of 50 treated at a public hospital in Brasilia over 5 years. Methods: we conducted a longitudinal, retrospective study, with 184 patients undergoing surgical procedures at the Asa Norte Regional Hospital (HRAN), including those who underwent only biopsy, between January 2013 and January 2018. We divided the patients into two groups: under the age of 50 (n=39) and age equal to or greater than 50 years (n=145). We compared the groups as to age, sex, symptoms, time between symptom onset and diagnosis, family and personal history, tumor location, histopathological characteristics, applied surgical management, staging and mortality. Results: the group of patients under the age of 50 had more individuals with stage III and IV (p=0.041), more frequent poorly differentiated tumors (10.25% versus 3.52%; p=0.153), and higher incidences of compromised surgical margins (p=0.368), angiolymphatic (p=0.07) and perineural (p=0.007) invasion, which denotes more advanced disease in this group of patients. Conclusions: the study showed the low effectiveness of population screening methods for colorectal cancer currently used in this population, given the high incidence of the disease and late diagnosis in both groups.

It is well established in the literature that the incidence of CRC increases significantly after the 5th decade of life and continues to increase with advancing age 3,4 . Although the recommended average age for starting screening is traditionally 50 years, more than 1/10 of cases of CRC (11% of colon tumors and 18% of rectal tumors) occur in individuals under 50, and the incidence and mortality have increased in this group 3-8 . In the United States, the incidence of CRC The data are inaccurate in Brazil, but studies have shown the same upward tendency in the incidence of colorectal cancer in young patients 10,11 . There are still

RESULTS
We included 184 patients in the study, of whom 39 (21.2%) were younger than 50 years old (Table 1).
and sex had no degree of association or dependence (p=0.32).

Risk factors
We  (Table 3).  were associated with the age group variable, that is, such symptoms were more frequent in patients under 50 years of age. Figure 1 shows the incidence of symptoms in both age groups.
relationship between the age group and the time from symptoms onset to diagnosis (p value > 0.05). The global mean time between symptom onset and diagnosis was 4.5 months, with a standard deviation of 7.9 months.

Tumor location
The location of the most frequent primary tumor was in the retosigmoid in both groups. Figure 2 shows the location of the primary tumor described in both groups. There was no statistical significance for this variable (p> 0.05).  In this context, we observed no statistical significant

Adopted surgical management
We further classified participants according to the applied surgical conduct. The most frequently adopted approach in both groups was rectosigmoidectomy.
In the group of patients under 50 years of age, we found that the number of left hemicolectomies (cancer surgery) was similar to the number of rectosigmoidectomies, both corresponding to 31% of cases. Figures 3 and 4 show the frequency of surgeries performed in each group.

Histopathological characteristics
The most frequent histological type in both groups was Adenocarcinoma (n=181). We classified patients according to the level of cell differentiation described in the histopathological examination.
In the group of patients under 50 years of age,  Table 5 shows the distribution of the characteristics studied according to age groups.
There was a higher incidence of perineural invasion (p=0.007) by primary tumors in patients under 50 years of age (Table 5).

Staging
Regarding clinical staging (CS), among patients under 50 years of age, there was a higher concentration of individuals with more clinically advanced disease, with 75% of cases (p=0.041) with stages III and IV in that group. As for patients over the age of 50, the most frequent stage was II, followed by IV, corresponding to 35.8% and 32.5% of the cases, respectively (Table 7). groups, with no statistical association between mortality and age (p=0.29). Several studies have described the increase in colorectal cancer in young people in recent decades, which has been attributed to inadequate screening, increased risk factors related to obesity and diet 2,9,24 . In the present study, there was a statistical association between obesity and the development of and 15% of CRC cases are diagnosed in this age group. Although patients in the group under 50 years of age had more advanced staging, the overall mortality rate was similar between the two groups. There was also no significant difference regarding recurrence. In a similar study, Schellerer et al. (2012) compared the clinical and histopathological characteristics of 244 patients aged 50 years or less with 1,718 patients aged over 50. They described that, although young patients have more aggressive histological subtypes and more advanced staging, cancer-related survival rates was similar 33,35 . In this regard, we should note that there were limitations of the study as to the length of patients' follow-up, requiring further research in this regard. It was also not possible to analyze specific mortality.

CONCLUSION
The majority of patients with colorectal cancer under the age of 50 years included in this study did not have a disease related to genetic and hereditary syndromes associated with CRC, were symptomatic, and received late diagnosis, mostly with clinical staging III and IV. We also found higher incidences of poorly differentiated tumors with compromised margins, angiolymphatic and perineural invasion in this population, which denotes more advanced disease.