Authored by Irami Araújo Filho*
Abstract
Colon cancer is a curable disease when restricted to the bowel and colectomy, the primary treatment. However, the presence and number of resected lymph nodes influence the therapeutic approach and prognosis of the patient. To evaluate the impact of the number of resected lymph nodes on the overall survival of patients treated for colon cancer at the League of Cancer Hospital - Natal - State of Rio Grande do Norte (RN) - Northeast Brazil. A retrospective observational study of 80 patients with colon cancer from Dr. Luiz Antônio Hospital (Natal-RN / Brazil), considering the period 2007-2014. Data were collected through medical records review. Survival rates were calculated and compared using the non-parametric Kaplan-Meier and Wilcoxon tests, respectively. All patients underwent radical surgical treatment associated or not with chemotherapy and/or radiotherapy treatment. The median survival time for the group of patients who had 12 or more resected lymph nodes was 9.4 years, in contrast to the 3.3 years of those who had less than 12 lymph nodes. Conclusion: It was concluded that a total of 12 or more resected lymph nodes confirmed by histopathology is associated with increased long-term survival in patients with colon cancer undergoing radical colectomy with or without chemotherapy and radiotherapy.
Keywords: Colonic neoplasms; Colorectal surgery; Lymph nodes; Lymphadenectomy; Lymph node excision; Survival analysis
Introduction
Colon cancer (CC) is one of the most prevalent neoplasms in the world. In Brazil, it is the fourth most common cancer. In 2018 the estimate of new cases was 36.360 (17.380 men/18.980women) [1]. Notwithstanding the high mortality, it is a curable disease when localized and restricted to the intestine [2]. The best therapeutic results are achieved through standard treatment, colectomy associated with lymphadenectomy (radical surgery). Cure occurs in up to 50% of patients when considering all stages of the disease. Nevertheless, relapse is still a major problem, contributing to the increase in deaths [3-5]. The prognosis and survival of each patient depend on correct staging, with TNM being the most used system. In this, the classification of “N” is given by the absolute number of metastatic lymph nodes (LN), where N1 will be considered from one to three lymph nodes and N2 above this value [6]. The presence of this lymph vascular invasion can distinguish stages II and III and alter the proposed treatment. According to current clinical evidence, adjuvant chemotherapy in the treatment of stage II-CC does not show an increase in survival, whereas, in stage III, its performance is indicated [4]. From this perspective, there would be impaired patient care if there were errors in lymph node count or histopathological positivity for malignancy [7].
Assessment of lymph node status is an alternative method, and one of the independent factors for the prognosis of WC. This is obtained by histopathological examination after radical surgery, in which reports express the number of resected lymph nodes (LNR) and the number of lymph nodes positive for tumor presence (LN+) [1,7-9]. Thus, in addition to lymphatic and vascular invasion, metastasis-free lymph nodes are considered a good prognostic factor. In addition to establishing proportionality, lymph node histological analysis provides additional information, such as the presence of extranidal extension (perinodal tumor cells), directly related to tumor aggressiveness [10].
The American Joint Committee on Cancer (AJCC) and the National Cancer Institute recommend that a minimum of 12 lymph nodes be examined in patients with CC to confirm the absence of lymph node involvement by the tumor [6]. This recommendation considers the number of LNs analyzed to be reflex of the radicality of lymph vascular mesenteric dissection in surgical resection and histopathological in the surgical specimen. In addition to being decisive for the elaboration of the therapeutic strategy of CC, the values of LNR and LN + are independent predictors that interfere with cancer outcomes. The overall survival and the likelihood of relapse, thus contributing to the definition of prognosis [11-13].
In this sense, it is essential to define the minimum number of LNs to be examined in a surgical specimen to determine the patient’s lymph node status as accurately as possible and to avoid sub staging, as the therapeutic approach is based on staging tumor completely. Based on the above, the present study evaluated the impact. It discussed the importance of quantifying the number of resected lymph nodes in the overall survival of patients diagnosed and treated for Colon Cancer in Natal, League of Cancer Hospital - State of Rio Grande do Norte. (RN) - Northeast Brazil.
Methods
A retrospective observational study of 80 patients was carried out at Dr. Luiz Antônio Hospital / League Against Cancer, a referral cancer hospital located in Natal - State of Rio Grande do Norte / Northeast Brazil, referring to the period between the years. From 2007-2014. The study was approved by the Research Ethics Committee of the League Against Cancer under protocol 044/044/2009, registered at Plataforma Brazil/National Commission of Research Ethics - CONEP/Ministry of Health. The study included all patients aged over 18 years with colon adenocarcinoma, confirmed by previous histopathological examination, who underwent radical surgery as a curative treatment, associated or not with radiotherapy and/or chemotherapy. Data were collected by reviewing medical records considering the following information: age, gender, origin, diagnosis, date of diagnosis (time of biopsy), TNM staging, type of surgical treatment, adjuvant treatment, disease recurrence, death´s age, and cause of death. All patients underwent surgical treatment alone or associated with chemotherapy and/or radiotherapy performed by members of the medical staff of Dr. Luiz Antônio Hospital. Cancer staging was performed following the TNM system, according to the American Joint Committee on Cancer. Overall survival was calculated considering the date of diagnosis. The non-parametric Kaplan-Meier and Wilcoxon methods were used to estimate and compare the overall survival rate using SPSS/IBM® version 25 statistical data analysis software. The results of the Wilcoxon test evidence were evaluated, considering the significance statistics level 5%.
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