Saudi Journal of Gastroenterology

ORIGINAL ARTICLE
Year
: 2009  |  Volume : 15  |  Issue : 1  |  Page : 18--23

Comparison of colorectal and gastric cancer: Survival and prognostic factors


Bijan Moghimi-Dehkordi, Azadeh Safaee, Mohammad R Zali 
 Research Center of Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Taleghani Hospital, Tabnak St., Yaman Ave., Velenjak, Tehran, Iran

Correspondence Address:
Bijan Moghimi-Dehkordi
Taleghani Hospital, Tabnak St., Yaman Ave., Velenjak, Tehran
Iran

Abstract

Background/Aims: Gastric and colorectal cancers are the most common gastrointestinal malignancies in Iran. We aim to compare the survival rates and prognostic factors between these two cancers. Methods: We studied 1873 patients with either gastric or colorectal cancer who were registered in one referral cancer registry center in Tehran, Iran. All patients were followed from their time of diagnosis until December 2006 (as failure time). Survival curves were calculated according to the Kaplan-Meier Method and compared by the Log-rank test. Multivariate analysis of prognostic factors was carried out using the Cox proportional hazard model. Results: Of 1873 patients, there were 746 with gastric cancer and 1138 with colorectal cancer. According to the Kaplan-Meier method 1, 3, 5, and 7-year survival rates were 71.2, 37.8, 25.3, and 19.5%, respectively, in gastric cancer patients and 91.1, 73.1, 61, and 54.9%, respectively, in patients with colorectal cancer. Also, univariate analysis showed that age at diagnosis, sex, grade of tumor, and distant metastasis were of prognostic significance in both cancers ( P < 0.0001). However, in multivariate analysis, only distant metastasis in colorectal cancer and age at diagnosis, grade of tumor, and distant metastasis in colorectal cancer were identified as independent prognostic factors influencing survival. Conclusions: According to our findings, survival is significantly related to histological differentiation of tumor and distant metastasis in colorectal cancer patients and only to distant metastasis in gastric cancer patients.



How to cite this article:
Moghimi-Dehkordi B, Safaee A, Zali MR. Comparison of colorectal and gastric cancer: Survival and prognostic factors.Saudi J Gastroenterol 2009;15:18-23


How to cite this URL:
Moghimi-Dehkordi B, Safaee A, Zali MR. Comparison of colorectal and gastric cancer: Survival and prognostic factors. Saudi J Gastroenterol [serial online] 2009 [cited 2020 Sep 30 ];15:18-23
Available from: http://www.saudijgastro.com/text.asp?2009/15/1/18/43284


Full Text

Malignancy is a major health problem in many countries throughout the world. [1] Nowadays, gastrointestinal-related cancers especially gastric cancer (GC) and colorectal cancer (CRC), form a vast bulk of overall malignant conditions. GC is one of the major causes of cancer-related death in the world, even though its incidence has decreased over the past decade. [2] The prognosis of GC is generally poor, especially in Western countries, [3],[4] where the overall survival rate at 5 years has not changed, oscillating between 8 and 26%, even though the resectability rate has increased (currently 60-80%). [5],[6],[7],[8],[9]

In recent years, cancer morbidity and mortality has increased in Iran, with GC becoming the second most common among all cancers. [10],[11] Similarly, CRC is the fourth commonest form of cancer occurring worldwide, with an estimated 783,000 new cases diagnosed in 1990, the most recent year for which international estimates are available. [12] CRC is the third most common cause of cancer-related death in the world. [13] The incidence of CRC in Iran is lower than that in Western countries, being the fifth and third most common cancer in men and women, respectively. However, its incidence in Iran is rising and has therefore become a significant public health issue. [14] Several variables representing pathological, clinical, and therapeutic characteristics have already been studied in numerous retrospective reports in an attempt to identify prognostic indicators in patients with GC [15],[16],[17],[18],[19],[20],[21] and CRC. [22],[23],[24],[25],[26],[27],[28],[29],[30],[31],[32],[33],[34] The aim of the present study is to compare the survival rates and prognostic factors in GC and CRC in one referral cancer registry in Iran.

 Patients and Methods



Between December 21, 2001 and December 21, 2006, 1873 patients with GC or CRC were registered in the cancer registry center of Research Center of Gastroenterology and Liver Disease (RCGLD), Shahid Beheshti Medical University; Tehran, Iran. Data on both cancers were collected using cancer registry forms and medical records of the patients. Two types of variables were analyzed in the survival analysis: (1) demographic variables including sex, age, family history of cancer and (2) clinical variables including histologic grade (degree of tumor differentiation) and presence of metastasis.

All patients were followed from their diagnosis until December 21, 2007 (as failure time) by telephone, and survival times were calculated in months. The survival curves were calculated according to the Kaplan-Meier Method and compared by the Log-rank test. Multivariate analysis of prognostic factors was carried out using the Cox proportional hazard model. SPSS.V.13 was used for all statistical calculations, and P [35]

The data used in this study were collected in a cancer registry belonging to the Research Center of Gastroenterology and Liver Diseases of Shahid Beheshti University of Medical Sciences, Tehran, Iran. This cancer registry serves as a major referral registry for the region.

Prognostic factors in GC [36],[37],[38],[39],[40],[41] and CRC [42],[43],[44],[45],[46],[47],[48],[49],[50],[51] are a source of controversy in many series. This study, based upon a prospective database, indicates that several patient- and tumor-related factors affect survival but are not independent prognostic factors. Compared with CRC, GC has a dismal prognosis and a low 5-year survival rate.

It is generally believed that young patients with CRC have a worse survival rate. Reports from Europe demonstrate that the 5-year survival rate for patients (30 years old or younger) is only 25-30%. [52],[53] Young patients are more likely to present with late-stage disease. The young patients also have higher-grade tumors [54] About 60-67% of young patients with CRC have a later stage (III/IV) disease, [53],[55] most of which are poorly differentiated or mucinous tumors [53],[54],[55],[56],[57] indicating a very poor prognosis. Other reports demonstrate that the 5-year survival rate of patients 30 years old or younger is around 40%. [58]

Also, some authors [59],[60],[61],[62] consider that age has prognostic value because young patients with GC have a poorer prognosis than older patients. Perhaps they present with more advanced disease because the index of suspicion for malignant disease is low and so the symptoms are allowed to progress for a longer period before investigation is considered, or there may be a greater biological activity of the tumor, which is more likely to be of the LaurŽen diffuse type.

In the present study, in the evaluation of demographic features, age at diagnosis was strongly associated with prognosis in the univariate analysis for both CRC and GC, but was not a significant prognostic factor in multivariate method for both cancers. In all age groups (≤ or > 50 yrs), CRC patients have a longer life than GC patients. Our results are in agreement with most other reports on GC [63],[64],[65],[66] and CRC [67],[68] which suggest that age at diagnosis significantly affects patient outcome.

Survival analysis indicated that gender is a prognostic factor for GC and CRC patients in the present study. Others have reported that, female patients with CRC compared with males showed a better outcome in the univariate analysis, but the overall survival was not significantly affected by these factors in the multivariate analysis. Our findings are in agreement with most series, [69],[70],[71],[72] though some controversies exist. [24],[73]

A study conducted in USA stated that GC females had better survival rates and that this was more apparent for early-stage tumors. [74] Curtis et al [75] reported that prognosis was better in females in their study, depending on the age and stage of diagnosis. However, no difference with respect to gender was observed in the survival rates for early-stage patients. Male patients had higher mortality rates in a study carried out on patients with GC in Canada [76] when the results were assessed regarding the gender for patients at the same stage (early stage). Another study reported no differences in survival rates regarding gender in patients at early or advanced stages. A study on 2773 patients with GC by the Rotterdam Cancer Registry reported similar resection rates for male and female patients. However, the same study demonstrated significantly lower postoperative mortality rates in female patients. [77] Jin-Pok Kim et al [78] stated that female patients had better prognosis in their study carried out on GC patients. Also a study stated no statistical differences in survival of patient on the basis of gender. [79]

With respect to the degree of cellular differentiation, the best prognosis has been found in well-differentiated groups in both tumors. [8],[9],[21],[25],[59] Patients with low-grade tumors had a greater survival rate than those with high-grade tumors, the difference being statistically significant.

Another important factor of prognosis was this study is distant metastasis. In univariate and multivariate analysis of both cancers, as expected, patients with metastasis to other organs have a poorer outcome. On the other hand, patients with distant metastasis had a risk of death about 2.25 and 1.92-fold of those without metastasis in GC and CRC, respectively. There are many reports that confirm our finding on GC [80],[81],[82] and CRC. [42],[44],[49],[50],[51],[83]

This study has some limitations as imposed by the retrospective nature of registry obtained data. For instance, we did not have access to important patient data such as macroscopic tumor type, depth of tumor invasion, and frequency of lymph node involvement. Also, no information was available on the rates of curative resection for the reason that patients under study were operated upon in different hospitals.

Although this study has highlighted the pertinent epidemiological and clinicopathological features of GC and CRC in Iran, further studies are needed to evaluate the environmental risk factors, incidence, the treatment outcomes, and long-term survival outcomes.

 Conclusion



According to our findings, survival rates in GC patients were lower than those in CRC patients. High prevalence of GC in Iran and its poor prognosis suggests that health care policy makers should be privy to such data for implementation of screening programs and resource allocation. Also, prognosis of disease is significantly related to histological differentiation of tumor and distant metastasis in CRC patients and only to distant metastasis in GC patients. It appears that these factors are associated with late diagnosis of disease, and therefore, planning and enforcement of screening programs is necessary for an early detection of these cancers.

 Acknowledgements



We thank Cancer registry center of Taleghani hospital for data gathering and Research Center of Gastroenterology and Liver Diseases for their valuable collaboration in this study.

References

1Parkin DM, Pisani P, Ferlay J. Estimates of the worldwide incidence of 25 major cancers in 1990. Int J Cancer 1999;80:827-41.
2Boring CC, Squires TS, Tong T, Montgomery S. Cancer statistics, 1994. CA Cancer J Clin 1994;44:7-26.
3Akoh JA, Macintyre IM. Improving survival in gastric cancer: Review of 5-year survival rates in English language publications from 1970. Br J Surg 1992;79:293-9.
4Wanebo HJ, Kennedy BJ, Chmiel J, Steele G Jr, Winchester D, Osteen R. Cancer of the stomach: A patient care study by the American College of Surgeons. Ann Surg 1993;218:583-92.
5Hangstvedt T, Viste A, Eide GE, Real C, Soreide O. The survival benefit of resection in patients with advanced stomach cancer: the Norwegian multicenter experience. World J Surg 1989;13:617-21.
6Gouzi HL, Huguier M, Fagniez PL, Lannois B, Flamant Y, Lacaine F, et al . Total versus subtotal gastrectomy for adenocarcinoma of the gastric antrum: A French prospective controlled study. Ann Surg 1989;209:162-6.
7Bozzetti F, Regalia E, Bonfanti G, Doci R, Ballarini D, Gennari L. Early and late results of extended surgery for cancer of the stomach. Br J Surg 1990;77:53-6.
8Salvon-Harman JC, Cady B, Nikulasson S, Khettry U, Stone MD, Lavin P. Shifting proportions of gastric adenocarcinomas. Arch Surg 1994;129:381-8.
9Stipa S, Di Giorgio A, Ferri M, Botti C. Results of curative gastrectomy for carcinoma. J Am Coll Surg 1994;179:567-72.
10Eskandar H, Hossein SS, Rahim M, Jalal H, Mehrdad A, Rajabi T. Clinical profile of gastric cancer in Khuzestan, southwest of Iran. World J Gastroenterol 2006;12:4832-5.
11Sadighi S, Raafat J, Mohagheghi M, Meemary F. Gastric cancer: 5 years experience of a single institute. Asian Pac J Cancer Prev 2005;6:195-6.
12Boyle P, Langman JS. ABC of colorectal cancer: Epidemiology. BMJ 2000;321:805-8.
13Parkin DM. Global cancer statistics in the year 2000. Lancet Oncol 2001;2:533-43.
14Islamic Republic of Iran, Ministry of Health and Medical Education, Office of Deputy Minister for Health Center for disease control, cancer office. Iranian annual National Cancer Registration Report. 2005-2006. March 2007.
15Cady B, Rossi RL, Silverman ML, Piccione W, Heck TA. Gastric adenocarcinoma: A disease in transition. Arch Surg 1989;124:303-8.
16Shiu MH, Perrotti M, Brennan MF. Adenocarcinoma of the stomach: A multivariate analysis of clinical, pathologic and treatment factors. Hepatogastroenterology 1989;36:7-12.
17Rohde H, Gebbensleben B, Bauer P, Stutzer H, Zieschang J; Findings from the German Gastric Cancer TNM Study Group. Has there been any improvement in the staging of gastric cancer? Cancer 1989;64:2465-81.
18Arveux P, Faivre J, Boutron MC, Piard F, Dusserre-Guion L, Monnet E, et al . Prognosis of gastric carcinoma after curative surgery: A population based study using multivariate crude and relative survival analysis. Dig Dis Sci 1992;37:757-63.
19Brems-Dalgaard E, Clausen HV. Survival following microscopically confirmed radical resection of N0 gastric cancer. Br J Surg 1993;80:1150-2.
20Bollschweiler E, Boettcher K, Hoelscher AH, Sasako M, Kinoshita T, Maruyama K, et al . Is the prognosis for Japanese and German patients with gastric cancer really different? Cancer 1993;71:2918-25.
21Michelassi F, Takanishi DM Jr, Pantalone D, Hart J, Chappell R, Block GE. Analysis of clinicopathologic prognostic features in patients with gastric adenocarcinoma. Surgery 1994;116:804-9.
22Mitry E, Douillard JY, Van Cutsem E, Cunningham D, Magherini E, Mery-Mignard D, et al . Predictive factors of survival in patients with advanced colorectal cancer: An individual data analysis of 602 patients included in irinotecan phase III trials. Ann Oncol 2004;15:1013-7.
23Newland RC, Dent OF, Lyttle MN, Chapuis PH, Bokey EL. Pathologic determinants of survival associated with colorectal cancer with lymph node metastases: A multivariate analysis of 579 patients. Cancer 1994;73:2076-82.
24Stower MJ, Hardcastle JD. The results of 1115 patients with colorectal cancer treated over 8-year period in a single hospital. Eur J Surg Oncol 1985;11:119-23.
25Park YJ, Park KJ, Park JG, Lee KU, Choe KJ, Kim JP. Prognostic factors in 2230 Korean colorectal cancer patients: Analysis of consecutively operated cases. World J Surg 1999;23:721-6.
26Mitry E, Bouvier AM, Esteve J, Faivre J. How to explain the improvement in survival for colorectal cancer? A French population-based study. Eur J Cancer 2003;1:S326.
27Martijn H, Voogd AC, van de Poll-Franse LV, Repelaer van Driel OJ, Rutten HJ, Coebergh JW, et al . Improved survival of patients with rectal cancer since 1980: A population-based study. Eur J Cancer 2003;39:2073-9.
28Scott NA, Wieand HS, Moertel CG, Cha SS, Beart RW, Lieber MM. Colorectal cancer: Dukes stage, tumor site, preoperative plasma CEA level and patient prognosis related to tumor DNA ploidy pattern. Arch Surg 1987;122:1375-9.
29Harrison LE, Guillem JG, Paty P, Cohen AM. Preoperative carcinoembryonic antigen predicts outcomes in node-negative colon cancer patients: A multivariate analysis of 572 patients. J Am Coll Surg 1997;185:55-9.
30Lee TL, Kim HD, Han WK, Pae WK, Kim KY. A clinical study of 1,037 Cases of colorectal cancer. J Korean Coloproctol Soc 1996;12:77.
31Yang HK, Kim SW, Park JG, Hong SC, Kim JP. Multivariate analysis of prognostic factors in colorectal cancer patients: Significance of lymph node metastasis as a prognostic factor in colorectal cancer. Korean J Gastroenterol 1991;23:440.
32Gardner B, Feldman J, Spivak Y, Panetta T, Fleischer J, Kasamblides E, et al . Investigations of factors influencing the prognosis of colon cancer. Am J Surg 1987;153:541-4.
33Takahashi K, Mori T, Yasuno M. Histologic grade of metastatic lymph node and prognosis of rectal cancer. Dis Colon Rectum 2000;43:S40-6.
34Cusack JC, Giacco GG, Cleary K, Davidson BS, Izzo F, Skibber J, et al . Survival factors in 186 patients younger than 40 years old with colorectal adenocarcinoma. J Am Coll Surg 1996;183:105-12.
35Ramos-De la Medina A, Salgado-Nesme N, Torres-Villalobos G, Medina-Franco H. Clinicopathologic characteristics of gastric cancer in a young patient population. J Gastrointest Surg 2004;8:240-4.
36Conti A, Tonini V. Factors influencing prognosis of gastric cancer after curative resection. G Chir 1989;10:303-7.
37Stipa S, Di Giorgio A, Ferri M, Botti C. Results of curative gastrectomy for carcinoma. J Am Coll Surg 1994;179:567-72.
38Shiu MH, Perrotti M, Brennan MF. Adenocarcinoma of the stomach: A multivariate analysis of clinical, pathologic and treatment factors. Hepatogastroenterology 1989;36:7-12.
39Bozzetti F, Bonfanti G, Morabito A, Bufalino R, Menotti V, Andreola S, et al . A multifactorial approach for the prognosis of patients with carcinoma of the stomach after curative resection. Surg Gynecol Obstet 1986;162:229-34.
40Adachi Y, Shiraishi N, Suematsu T, Shiromizu A, Yamaguchi K, Kitano S. Most important lymph node information in gastric cancer: Multivariate prognostic study. Ann Surg Oncol 2000;7:503-7.
41Haugstvedt TK, Viste A, Eide GE, Soreide O. Norwegian multicentre study of survival and prognostic factors in patients undergoing curative resection for gastric carcinoma: The Norwegian Stomach Cancer Trial. Br J Surg 1993;80:475-8.
42Liang JL, Wan DS, Pan ZZ, Zhou ZW, Chen G, Li LR, et al . Multivariate regression analysis of recurrence following curative surgery for colorectal cancer. Ai Zheng 2004;23:564-7.
43Yamamoto Y, Takahashi K, Yasuno M, Sakoma T, Mori T. Clinicopathological characteristics of skipping lymph node metastases in patients with colorectal cancer. Jpn J Clin Oncol 1998;28:378-82.
44Hojo K, Koyama Y. Postoperative follow-up studies on cancer of the colon and rectum. Am J Surg 1982;143:293-3.
45Xu FY, Di MJ, Dong JK, Wang FJ, Jin YS, Zhu YM, et al . Influence of clinical and pathomorphological parameters on prognosis in colon carcinoma and rectal carcinoma. Zhejiang Da Xue Xue Bao Yi Xue Ban 2006;35:303-10.
46Compton CC, Fielding LP, Burgart LJ, Conley B, Cooper HS, Hamilton SR, et al . Prognostic factors in colorectal cancer: College of American Pathologists Consensus Statement 1999. Arch Pathol Lab Med 2000;124:979-94.
47Berti Riboli E, Secco GB, Lapertosa G, Di Somma C, Santi F, Percivale PL. Colorectal cancer: Relationship of histologic grading to disease prognosis. Tumori 1983;69:581-4.
48Nilsson KR, Berenholtz SM, Dorman T, Garrett P, Kaufman HS, Pronovost PJ. Preoperative predictors of blood transfusion in colorectal cancer surgery. J Gastrointest Surg 2002;6:753-62.
49Liang H, Wang XN, Wang BG, Pan Y, Liu N, Wang DC, et al . Prognostic factors of young patients with colon cancer after surgery. World J Gastroenterol 2006;12:1458-62.
50He WJ, Wang L, Hu H, Kang SY, Qian HX, Xu FM. Correlation of invasion, metastasis, and prognosis in low and middle rectal cancer. Ai Zheng 2002;21:1222-5.
51Enderlin F, Gloor F. Colorectal cancer: The relationship of staging to survival: A cancer registry study of 800 cases in St Gallen-Appenzell. Soz Praventivmed 1986;31:85-8.
52Miyake Y, Mishima H, Nishisho I, Kikkawa N, Monden M. Use of microsatellite analysis in young patients with colorectal cancer to identify those with hereditary nonpolyposis colorectal cancer. J Surg Oncol 2002;79:157-65.
53Bedikian AY, Kantarjian H, Nelson RS, Stroehlein JR, Bodey GP. Colorectal cancer in young adults. South Med J 1981;74:920-4.
54O'Connell JB, Maggard MA, Liu JH, Etzioni DA, Ko CY. Are survival rates different for young and older patients with rectal cancer? Dis Colon Rectum 2004;47:2064-9.
55Minardi AJ Jr, Sittig KM, Zibari GB, McDonald JC. Colorectal cancer in the young patient. Am Surg 1998;64:849-53.
56Taylor MC, Pounder D, Ali-Ridha NH, Bodurtha A, MacMullin EC. Prognostic factors in colorectal carcinoma of young adults. Can J Surg 1988;31:150-3.
57Shahrudin MD, Noori SM. Cancer of the colon and rectum in the first three decades of life. Hepatogastroenterology 1997;44:441-4.
58Liang Han. Prognosis factors for patients with colorectal cancer. In: Xishan H, Dianchang W, editors. Abdominal Oncology. Beijing: People's Health Press; 2003. p. 519-27.
59Matley PJ, Dent DM, Madden MV, Price SK. Gastric carcinoma in young adults. Ann Surg 1988;208:593-6.
60Mitsudomi T, Matsusaka T, Wakasugi K, Takenaka M, Kume K, Fujinaga Y, et al . A clinicopathological study of gastric cancer with special reference to age of the patients: An analysis of 1630 cases. World J Surg 1989;13:225-30.
61Maehara Y, Oshiro T, Oiwa H, Oda S, Baba H, Akazawa K, et al . Gastric carcinoma in patients over 70 years of age. Br J Surg 1995;82:102-5.
62Maehara Y, Watanabe A, Kakeji Y, Emi Y, Moriguchi S, Anai H, et al . Prognosis for surgically treated gastric cancer patients is poorer for women than men in all patients under age 50. Br J Cancer 1992;65:417-20.
63Lo SS, Wu CW, Chen JH, Li AF, Hsieh MC, Shen KH, et al . Surgical results of early gastric cancer and proposing a treatment strategy. Ann Surg Oncol 2007;14:340-7.
64Borie F, Rigau V, Fingerhut A, Millat B. French Association for Surgical Research. Prognostic factors for early gastric cancer in France: Cox regression analysis of 332 cases. World J Surg 2004;28:686-91.
65Mitsudomi T, Matsusaka T, Wakasugi K, Takenaka M, Kume K, Fujinaga Y, et al . A clinicopathological study of gastric cancer with special reference to age of the patients: An analysis of 1630 cases. World J Surg 1989;13:225-30.
66Faivre J, Forman D, Esteve J, Gatta G. Survival of patients with oesophageal and gastric cancers in Europe. Eur J Cancer 1998;34:2167-75.
67Kosmidis PA, Tsavaris N, Skarlos D, Theocharis D, Samantas E, Pavlidis N, et al . Fluorouracil and leucovorin with or without interferon a-2b in advanced colorectal cancer: Analysis of a prospective randomized phase III trial. J Clin Oncol 1996;14:2682-7.
68Newland RC, Dent OF, Lyttle MN, Chapuis PH, Bokey EL. Pathologic determinants of survival associated with colorectal cancer with lymph node metastases: A multivariate analysis of 579 patients. Cancer 1994;73:2076-82.
69Wiggers T, Arends JW, Volovics A. Regression analysis of prognostic factors in colorectal cancer after curative resections. Dis Colon Rectum 1987;51:33.
70Hannisdal E, Thorsen G. Regression analyses of prognostic factors in colorectal cancer. J Surg Oncol 1988;37:109-12.
71Roncucci L, Fante R, Losi L, Di Gregorio C, Micheli A, Benatti P, et al . Survival for colon and rectal cancer in a population based cancer registry. Eur J Cancer 1995;32A:295.
72Wolmark N, Weinard HS, Rockette HE, Fisher B, Glass A, Lawrence W, et al . The prognostic significance of tumor location and bowel obstruction in Dukes B and C colorectal cancer. Ann Surg 1987;198:743.
73Griffin MR, Bergstralh EJ, Coffey RJ, Beart RW Jr, Melton LJ 3rd. Predictors of survival after curative resection of carcinoma of the colon and rectum. Cancer 1987;60:2318-24.
74Miller BA, Ries LA, Hankey BF, Kosary CL, Edwards BK, editors. Cancer statistics Review: 1973-1989. NIH Pub. No. 92-2789 Bethesda, National Cancer Institute 1992;23:1-9.
75Curtis RE, Kennedy BJ, Myers MH, Hankley BF. Evaluation of AJC gastric cancer staging using the SEER population. Semin Oncol 1985;12:21-31.
76Bako G, Ferenczi L, Hanson J, Hill GH, Dewar R. Factors influencing the survival of patients with cancer of the gastric. Clin Invest Med 1985;8:22-8.
77Damhuis RA, Tilanus HW. The influence of age on resection rates and postoperative mortality in 2773 patients with gastric cancer. Eur J Cancer 1995;31:928-33.
78Kim JP, Lee JH, Kim SJ, Yu HJ, Yang HK. Clinicopathologic characteristics and prognostic factors in 10783 patients with gastric cancer. Gastric Cancer 1998;1:125-33.
79Yokota T, Kunii Y, Saito T, Teshima S, Yamada Y, Iwamoto K, et al . Prognostic factors of gastric cancer tumors of less than 2 cm in diameter: Rationale for limited surgery. Eur J Surg Oncol 2002;28:209-13.
80Zhang XF, Huang CM, Lu HS, Wu XY, Wang C, Guang GX, et al . Surgical treatment and prognosis of gastric cancer in 2,613 patients. World J Gastroenterol 2004;10:3405-8.
81Koga H, Ochiai A, Nakanishi Y, Sasako M, Mizuno S, Kinoshita T, et al . Reevaluation of prognostic factors in gastric leiomyosarcoma. Am J Gastroenterol 1995;90:1307-12.
82Moriguchi S, Kamakura T, Odaka T, Nose Y, Maehara Y, Korenaga D, et al . Clinical features of the differentiated and undifferentiated types of advanced gastric carcinoma: Univariate and multivariate analyses. J Surg Oncol 1991;48:202-6.
83Oya M, Takahashi S, Okuyama T, Yamaguchi M, Ueda Y. Synchronous colorectal carcinoma: clinicopathological features and prognosis. Jpn J Clin Oncol 2003;33:38-43.