Treatment results and some predictors 1. Early results

4.3.1.1. Treatment method

69% of patients underwent the surgency for anal sphincterotomy protection; Only 31.0% of patients underwent the surgency for rectum resection, which destroys anal sphincterotomy. 25.9% of patients undergo laparoscopic surgery and 74.1% of patients underwent open surgery.

Our study result is consistent with that of other studies. According to Mai Dinh Dieu, the proportion of patients who underwent the surgency for anal sphincterotomy protection is 56.8%; the proportion of patients who underwent the surgency for rectum resection, which destroys anal sphincterotomy is 43.2%. According to Nguyen Van

Hieu, the proportion of patients who underwent the surgency for anal sphincterotomy protection in the prospective and restrospective studies is 49.6% and 41.0%, respectively.

4.3.1.2. Accidents and complications

In our study, there are 22 (19.9%) patients with accidents and complications, accounting for 19.9%; There is 1 (0.9%) patient who died of septic shock, toxic shock, peritonitis/anastomotic Dehiscence.

Our study result is consistent with the results of other studies.

According to Nguyen Minh An et al, the surgical accidents and complications is 9.7% and 10.9%, respectively and there is no mortality in the surgery. According to Leonard D. et al, postoperative complications is 19.9%, anastomotic dehiscence of 6.8% and mortality of 0.6%. The study of Dent O.F. et.al on 5217 colorectal-cancer patients who underwent radical surgery during 1971-2013 period in Australia showed that 22.5% of patients underwent a medical complication, which tended to gradually decrease year by year, at an average level of 35.5% in the 1976-1979 period to 22.6%

in the 2010-2013 period.

Such as, surgical method for resection of rectum and entire mesorectum has a mild and manageable ratio of accidents and complications.

4.3.1.3. Results of regional lymph node dissection - Results of dissected lymph node

The total number of dissected lymph nodes is 1449; Average number of dissected lymph nodes per patient is 12.5 ± 3.6; The maximum number of lymph nodes per patient is 24; The minimum number of lymph nodes per patient is 4.

The average number of lymph nodes per patient in our study is consistent with that of other studies. According to the study of Dejardin O. et al on 4197 colorectal-cancer patients in the 1997-2004 period in France, the average number of dissected lymph nodes per patient is 12.00 (12.75-12.24 lymph nodes). According to the study of Choi H.K. et. al on 664 colorectal-cancer patients of stage II, who underwent the surgery, the average number of examined lymph nodes is 12 (1-58). According to the study of Li Q., et al., on 2256 colorectal-cancer patients of stage III, the average number of dissected lymph nodes per patient is 15.0 (12-19).

The number of lymph nodes is related to a number of factors such as: the study duration, the age of the disease, the level of tumor

invasion, the degree of tumor differentiation, lymph node metastasis, stage of disease, level and experience of surgeon.

4.3.2. Deeper results

4.3.2.1.

o

verall survival in 3 years

Regarding on overall survival in 3 years, it can be seen that the proportion of patients who underwent overall survival in 3 years in our study is 91.7%; The average survival time is 48.9 months (Table 3.33).

The overall survival in 3 years of the patients in our study is higher than that of other studies. The study of Hassan M.R. and et al on 1214 colorectal-cancer patients in 2008-2009 period showed that the overall survival in 3 years is 59.1%. Mehrkhani F. et al. made the study on 1090 colorectal-cancer patients who underwent surgery in 1999-2002 period, the average survival duration of all patients is 42.8 months. The proportion of patients who underwent entire survival in 3 years is 54%.

The proportion of patients who underwent overall survival in 3 years in our study is higher than the results of some above studies. The reason may be that our study subjects included rectal-cancer patients who have undergone radical surgery (excluded the patients with late-stage disease). Patients in the late late-stage) while the objects of the above studies are all rectal-cancer patients (included patients with late-stage disease, who can’t attend radical surgency).

- Longer survival based on the lymph node size

The three-year overall survival rate of the patients with the lymph node size <10 mm (96,7%) is higher than that of the patients with the lymph node size ≥10 mm (78,4%) (p<0,05)

Our study result is consistent with those of other studies.

According to Dhar DK et al, the proportion of entire survival in 5 years in the groups of patients with metastatic lymph node in the size≤9 mm and ≥10 mm, is 63.5% and 42.5%, respectively (p <0.001).

Komori et al. made a study of the metastatic lymph nodes, in which each lymph node is centrally sliced and microscopically measured to obtain the largest slice area and the lymph nodes are divided into groups with the gradually increasing slice area: Na (area <4mm2), Nb (area of 4-25 mm2), Nc (area of 25-100 mm2) and Nd (area> 100 mm2). Such researchers found that the 5-year survival rate gradually decreased when slice area of lymph nodes increased gradually; The 5-year survival rate of Na, Nb, Nc, Nd is 77.8%, 63.9%, 18.8% and 12.8%, respectively.

Thus, the size of lymph nodes is significantly associated with survival rate of rectal-cancer patients. The proportion of entire survival in 3 years of the patients with the lymph node size ≥10 mm is lower than that of the patients with the lymph node size <10 mm (p <0,05).

- Longer survival based on the regional lymph node classification ((according to AJCC 2010)

In our study, the rate of overall survival in 3 years of the patients with no metastasis of regional lymph node (pN0), metastasis of 1-3 regional lymph node (pN1), metastasis of >= 4 regional lymph node (pN2) gradually decreased to 97.1%; 71.9% and 50.0%, respectively.

Our study result is consistent with the data of other studies.

According to Balta A.Z, there is a significant relationship between survival rate and regional lymph node classification (p<0.001). According to HassanM.R. et.al, the 3-year

o

verall survival rate of the patients with the stages of regional lymph nodes N0, N1, and N2 77.4%, 58.4% and 36.2%, respectively (p <0.001).

Accoring to the combined analysis of 3 studies, including 2008 rectal-cancer patients by Gunderson L.L. et.al, the survival rate gradually decreased when the number of metastatic lymph nodes gradually increased; The 5-year survival rate of the patients with the stages of regional lymph nodes N0, N1, N2 group is 73%, 65%, 52%

(p <0.001), respectively.

Thus, the regional lymph node is closely related to the 3-year survival rate of all rectal-cance patients. The 3-year survival rate of all rectal-cance patients significantly reduced when regional lymph node metastasis happens and when the number of regional lymph node metastasis increased, and vice versa (p <0.001).

- Longer survival in disease stages

The three-year overall survival rate of the patients in the disease stages I-II (97,1%) is higher than that of the patients in the disease stage III (71,6%) (p is <0,001). Our study result is consistent with those of other studies.

According to the study on 2720 colorectal-cancer patients at 11 cancer centers throughout Europe by Gatta G. et.al, the survival duration is closely related to the disease stage at diagnosis. The study results by O'Connell J.B. showed that the survival duration in stage I, II, III and IV is 93.3%, 82.5%, 59.5% and 8.1%, respectively. Hassan M.R. and et.al, the three-year entire survival rate of the patients in stage I, II, III and IV is 77.0%, 78.0%, 54.6%, 33.9%, respectively (p <0.001).

The results of our study showed that the three-year survival rate is closely correlated with the disease stages. The later the disease stage is, the lower the survival rate is and vice versa (p <0.001).

- Multivarite regression analysis of survival and risk factors

The multivariate regression analysis showed that the three-year survival rate of the patients with the tumor size <3/4 its perimeter is 21.3 times than that of patients with the tumor size ≥ 3/4 its perimeter (P<0.05). As such, the tumor covering the area ≥ 3/4 its perimeter is an independent predictor related the survival of patients..

CONCLUSION 1. Features of lymph node metastasis and risk factors

- The most popular symptoms are: Bloody faeces: 91.7%, Feeling hard to go to stool: 86,1%; Changes in faeces shape: 86,1%, Changing bowel habits: 75,9%.

- The preoperative CEA concentration ≥ 5 ng/ml accounteed for 55,6%.

- Histopathology: Modreate differentiation accounted for the highest proportion: 83.3%; Highly and poor differentiation accounted for minor proportion of 11.1% and 5.6%, respectively.

- Tumors invading through serosa (T4) accounted for the highest rate: 63.9%; and followed by T3: 27.8%; T2: 8.3%; No case is pT1.

- The rate of lymph node metastasis is 31%; of which, N1 is 25.9%; N2 is 5.2%.

- By testing the lymph node micro-metastasis through immunohistochemistry, 23.8% is found to have suffered from micro-metastatic lesions.

- The risk of lymph node metastasis of high and medium rectal cancer is 3.6 times higher than that of low rectal cancer. The risk of lymph node metastasis of the tumor covering the area> 1/2 its perimeter causes is 2.6 times higher than that of the tumor covering the area ≤ 1/2 its perimeter. The CEA concentration >10 ng/ml causes the higher risk of lymph node metastasis by 3.08 times than the CEA concentration ≤ 10 ng/ml. The risk of lymph node metastasis of the patients with lymph node in the size ≥ 10 mm is 209.7 times higher than that of the patients with lymph node in the size <10 mm. The multivariate regression analysis showed that the lymph node size ≥ 10 mm is an independent predictor related to lymph node metastasis.

2. Treatment results of the studied group of patients

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