5-year survival and prognostic factors for resectable colon cancer: a single institution experience in Lebanon
Rhea Mattar , Fadi El Karak , Ernest Diab * Marwan Ghosn
Department of Hematology-Oncology, Universite Saint-Joseph, Faculte de medecine, Beirut, Lebanon
Ernest Diab, Department of Hematology-Oncology, Universite SaintJoseph, Faculte de medecine, Beirut, Lebanon.
Rhea Mattar and Fadi El Karak contributed equally
Figure 1. Flowchart of patients included in the study
The protocol and all the study procedures were approved by the ethics committee of Saint-Joseph University in Beirut. The Helsinki declarations of 1963 were considered: respect, confidentiality, and patient anonymity.
Data were analyzed using SPSS software version 29. The categorized variables were compared by Pearson’s χ² test, and quantitative variables were compared by the Student’s t-test. OS and PFS were analyzed using the Kaplan–Meier method. P values less than 0.05 were considered statistically significant.
Impact of cancer stage on survival after colectomy
The OS rate at 5 years was 100% for stage I tumors, 92.7% for stage II and 73.9% for stage III, with a significant difference (p = 0.02). The median 5-year survival was 76.7 months for stage I tumors, 66.9 months for stage II and 53.0 months for stage III. The PFS was 74.6 months for stage I, 64.6 months for stage II and 48.2 months for stage III. Patients with stage I CC had higher 5-year OS (figure 2-A) and PFS (figure 2-B) than patients with stage II and stage III, with a significant difference (p = 0.003 for OS and p = 0.01 for PFS)
Figure 2. Kaplan-Meier curves of OS (A) and PFS (B) of CC after curative surgery, at stages I, II and III.
Impact of cancer sidedness on survival after colectomy
Clinical and pathological characteristics depending on the sidedness of cancer
Among the patients included, 42 (53.2%) had a right-sided colon cancer (RCC) and 37 (46.8%) had a left-sided colon cancer (LCC). The baseline characteristics of patients with RCC and LCC are shown in table 1.
Patients with RCC were older at the time of colectomy than patients with LCC (67.7 years versus 64.3 years, p=0.26) and the majority were females (57.1% versus 35.1%, p=0.05). A lower BMI was noted in patients with RCC compared to those with LCC (24.6 ± 4.3 vs 26.8 ± 4.7, p = 0.04) (table 1).
The distribution of the different histological types is shown in Table 1. Conventional adenocarcinoma has a higher tendency to occur in the left colon (89.2% vs 61.9%) rather than in the right colon. However, mucinous-type adenocarcinoma has a higher tendency to occur in the right colon (37.5% vs 8.1%) rather than in the left colon. This trend is statistically significant with a χ² test giving a p-value equal to 0.01. The most frequent location was in the cecum (20%) for RCC and in the sigmoid colon (42%) for LCC (table 1).
Tumors of patients with RCC had larger size (5.1 ± 1.7 (2 – 8.5) vs 4.4 ± 1.3 (2.5 – 8), p = 0.05) and more advanced histological grade (31% vs 8% at grades 3 and 4, p = 0.012) than tumors of patients with LCC. The tumors of patients with LCC were mostly stage T1 and T2 (37.8% vs 11.9%, p = 0.05) while those of patients with RCC were mostly stage T3 and T4 (88.1% vs 62.1%, p = 0.05). Patients with RCC had more advanced N stage (38.1% vs 18.9% at stages N1 and N2, p=0.13) and more advanced AJCC cancer stage (38.1% vs 18.9% at stage III, p=0.03) than patients with LCC. Regarding lymph node involvement, the number varied between 0 and 10 positive nodes for RCC, and between 0 and 4 positive nodes for LCC (p = 0.006). No significant difference was observed regarding lymphatic, vascular or perineural invasion between RCC and LCC. A higher percentage loss of MMR protein expression was observed in patients with RCC (23.8% vs 5.4%, p = 0.023) compared to those with LCC (table 1).
Among the operated patients, 8 patients (19.0%) with RCC and 6 patients (16.2%) with LCC developed a recurrence after colectomy (p = 0.74). Regarding the location of metastases, liver metastases (66.7% vs 60.0%, p = 0.7) and peritoneal carcinomatosis (33.3% vs 20.0%, p = 0.7) were more frequent for LCC, while pulmonary location was more frequent for the RCC (20.0% vs 0%, p = 0.7) (table 1).
Survival analysis of RCC and LCC after colectomy
The OS rate at 5 years was 83.3% for RCC and 94.6% for LCC (p = 0.1). Patients with LCC showed higher survival time (69.4 ± 10.1 (45 – 83.8) vs 60.7 ± 16.1 (4 – 84), p = 0.01) than those with RCC. For PFS, the median duration was 57.7 months for RCC and 66.3 months for LCC. Patients with LCC had a higher 5-year OS (figure 3-A) and PFS (figure 3-B) than patients with RCC (p= 0.296 for OS and p = 0.380 for PFS).
Figure 3. Kaplan-Meier curves of OS (A) and PFS (B) of RCC and LCC after curative surgery, at any stage.
Impact of cancer grade on survival after colectomy
Concerning the distribution by grades and the impact on survival after colectomy, the median 5-year survival was 68.8 months for grades 1 and 2 tumors and 48.7 months for grades 3 and 4 tumors (p < 0.001). Figure 4 represents a box plot showing the difference in survival between the 2 groups of grades.
Figure 4: Box plot showing median survival in months as a function of cancer grades at the time of colectomy.
Impact of tumor size on survival after colectomy
Regarding the impact of tumor size at the time of colectomy on survival, we obtained a weak negative correlation with a correlation coefficient equal to -0.2. This result is represented by a scatterplot (figure 5) showing a non-significant correlation (p = 0.09).
Figure 5: Scatterplot showing the relationship between tumor size at the time of colectomy and median survival in months.
Impact of patient age at colectomy on survival after colectomy
By studying the impact of the patient's age at the time of colectomy on survival, we obtained a moderate negative correlation with a correlation coefficient equal to -0.1. This result is represented by a scatterplot (figure 6) showing a non-significant correlation (p = 0.60).
Figure 6: Scatterplot showing the association between patient age at colectomy and survival in months.
Impact of different tumor factors on survival after colectomy
The presence of lymphatic, vascular or perineural invasion at the time of colectomy was associated with a lower median survival at 5 years (table 2). This association was significant for vascular invasion only (p = 0.02).
Table 2: Association between survival and various tumor factors. Values are presented as mean ± standard deviation. The values in bold are those considered significant for a p value less than 0.05.
Impact of taking adjuvant treatment on survival after colectomy
Patients with stage II CC who received adjuvant CT had a higher 5-year OS (figure 7-A) and PFS (figure 7-B) than patients with stage II CC who didn’t receive CT (p= 0.287 for OS and p = 0.206 for PFS).
Figure 7: Kaplan-Meier curves of OS (A) and PFS (B) of stage II CC depending on taking adjuvant CT.