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Showing 2 results for Cox Proportional Hazards Model

H Zeraati , M Mahmoudi , K Mohammad, A Kazemnejad, M.a Mohagheghi , M.r Mir ,
Volume 3, Issue 4 (7-2005)
Abstract

In recent years the patterns of mortality have changed in Iran, and cancers are playing a greater role in this regard in this country. Various reports indicate that gastric cancer is highly prevalent it is the second most common cancer in men, and fourth in the general population. The purpose of this study was to determine the five-year survival rate of gastric cancer patients who had undergone surgical treatment at one of the most important cancer treatment centers, the Iran Cancer Institute, and to assess its associated factors. Three hundred and 30 patients with gastric cancer who had been admitted to and operated on at the Iran Cancer Institute between January 1996 and April 2000 were enrolled in this study. The patients’ life expectancy after surgery was determined, and its relationship with variables of age at the time of surgery, gender, and factors related to the disease such as the cancer site, pathologic type, stage, presence of metastasis, and sites of metastases were assessed. The five-year survival rate and the median life expectancy in the studied patients were 23.6% and 19.90 months, respectively. Univariate analysis showed that gender, cancer site, and pathologic type did not affect life expectancy significantly. But the five-year survival rate significantly decreases with age. As expected, those involved with metastasis had a significantly lower five-year survival rate, and the disease stage significantly affected the patients’ life expectancy (P<0.001). The Cox proportional hazards model was used to assess the effect of different variables simultaneously, and it showed that age, distance metastasis, and disease stage influenced the rate of survival. Gastric cancer patients in Iran have a low five-year survival rate. One of the most important reasons seems to be delayed consultation and diagnosis. Most patients are seen first with the disease in the late stages. At this point, most have lymph node and liver metastasis which makes treatment even more complex. Thus, it is necessary to employ mass media for extensive public education about the early warning signs of the disease and performing periodic examinations.
M Behzadpoor, H Zeraati, M Mahmoudi, A Rahimi,
Volume 7, Issue 1 (8-2009)
Abstract

Background and Aim: Like other cancers, gastric cancer is due to uncontrolled growth of tissues. Although there are different therapy methods to treat it, such as surgery, radiation therapy, chemotherapy, and multimodality therapy, relapse and death may occur. Reports show that in Iran gastric cancer is the first cause of death among deaths due to cancers. The purpose of this study was to determine the two-year survival rate after relapsing and its associated factors among gastric cancer patients who had undergone surgical treatment in Iran Cancer Institute, one of the most important cancer treatment centers in Iran.

Methods and Materials: A total of 330 patients with gastric cancer who had been admitted to and operated on at the Iran Cancer Institute between January 1996 and April 2000 were enrolled in this study. The patients' life expectancy after relapse was determined. Survival was defined as the elapsed time between the two successive events, relapse and death, neither of which can be determined exactly therefore the data are doubly censored failure time data. Thus, the relationships between life expectancy at relapse and such variables as age, gender, and factors related to the disease, such as the cancer site, pathologic type, stage, and sites of metastases were determined using the Cox proportional hazards model.

Results: The two-year survival rate after relapsing and the median life expectancy after relapsing were 15% and 10.15 months, respectively. Univariate analysis showed that except disease stage, no other variable (age, gender, cancer site, pathologic type and sites of metastases) affected life expectancy after relapsing significantly. The Cox proportional hazards model for doubly censored failure time data showed that age, gender, and pathologic type had the highest influence, in a decreasing order, on the rate of survival after relapsing.

Conclusion: Two-year survival rate after relapsing is very low in gastric cancer patients. One of the most important reasons seems to be delayed consultation and diagnosis. Most patients seek medical advice first with the disease in the late stages, when most have lymph node, liver or even distant metastasis which makes treatment even more complex, and when the risk of relapse and death would be increased. Thus, early diagnosis and therapy for a common stomach illness could help prevent a potential gastric cancer.



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