Journal of School of Public Health and

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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.

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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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Background and Aim: The most common cancer in Iran is digestive system cancer, the highest incidence of which is reported from the Caspian Sea littoral. This study aimed to determine factors affecting the survival of patients with gastrointestinal cancer using the Cox and parametric models the 2 models were compared.

Materials and Methods: This survey was a prospective study conducted between 1990 and 1991. Data were collected through the Cancer Registry Center in Babol, which functions under supervision of the School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences. We tried to identify cases of gastrointestinal cancers. The individual characteristics of 484 patients, namely, age, sex, family history, marital status, smoking status, occupation, ethnicity, medication status, education, residence (urban, rural), and type of cancer were recorded. The patients were followed up for a period of 15 years, i.e., until 2006 year. To determine the effective factors on survival of patients, the Cox model and parametric models such as exponential, weibull, log-normal, log-logistic, and the AIC criteria and residuals were used to compare the effectiveness of the models. The SAS and STATA software were used for data analysis, with a significant level of 0.05.

Results: Sixty-six percent of the patients (total n=484) were males and 34% females, with a mean age of 59 and 55 years, respectively. Their distribution according to type of cancer was as follows: esophageal cancer, 359 (74.2%) stomach cancer, 110 (22.7%) colorectal cancer, 15(3.1%). Estimated one-, three-, and five-year survival rates were 24%, 16% and 15%, respectively.

Conclusion: The results of this study reveal that gender and family history can be strong risk factors for GI cancer. Log-normal and log-logistic models in multivariate and univariate analyses gave almost similar results. However, based on AIC criteria and residuals analysis, the log-logistic model gives the best fit as compared to other parametric models and can be used instead of the Cox model for determining factors affecting survival of patients with gastrointestinal tract cancer.

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Background and Aim: Length of stay (LOS) in a hospital is one of the best hospital indicators that can be used for various purposes. In this survey, we studied the hospital LOS and its associated factors in Tehran University of Medical Sciences Women's Hospital (a teaching hospital) in Tehran using the Cox proportional hazards semi parametric model and compared the results with the results obtained using the multiple linear regression.

Materials and Methods: This was a descriptive-analytical study in which we reviewed 3421 files of inpatients hospitalized in, and those discharged from, the oncology, surgery and obstetrics units in 2008. The required data were collected using a data collection sheet and inpatient interviews. A P<0.05 was considered statistically significant.

Results: The median of patients' LOS in the hospital was 50.8 hours, that in the obstetrics, surgical and oncology units being 48.5, 54.4 and 94.2 hours, respectively. Of all the patients, 2632 (76.9%) had been discharged with a recovery status and the rest (23.1%) with a no-recovery status. Results of the Cox proportional hazards model showed that the following variables had increased LOS: a distance longer than 200 km between a patent's residence and the hospital, hospitalization in the surgery and oncology units, admission on a Thursday, admission by an internist, hospitalization for neoplastic, endocrine, nutritional, or genitourinary system diseases (P<0.005), as well as a high number of diagnostic laboratory tests, radiographies or sonographies (P<0.001). Patients admitted and hospitalized as an emergency case had a shorter LOS (P<0.001) than others. On the other hand, based on the multiple linear regression model results, some occupations (being a worker, a farmer, a stockbreeder, or a retired spouse) admission on a Thursday, (The first day of the weekend in Iran), suffering from a neoplastic disease, and a high number of diagnostic tests or radiographies or sonographies increased, and admission by a resident decreased, patients' LOS (P<0.05).

Conclusion: Considering having censored data, the Cox proportional hazards model is a more suitable model than the multiple linear regression models for identifying factors influencing patients' LOS in a hospital. From among the LOS Cox model's associated factors as identified in this study, policy-makers and managers can only change admission days and the number of diagnostic tests. That is to say, they should try to prevent admission on a Thursday (unless emergency cases) and also perform the required primary diagnostic tests before admitting a patient into the hospital, which would lead to a more effective utilization of hospital beds and other resources.

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  Background and Aim: The objective of this study was to determine factors associated with time to relapse and, thus, retention time, of a cohort of opioid-dependents under methadone maintenance treatment, using survival models, in the Iranian National Center for Addiction Studies (INCAS).

  Materials and Methods: A total of 198 opioid-dependent clients participating in the Methadone Maintenance Treatment Program, implemented by INCAS between April 2007 and March 2011, were included in the study. A Cox proportional hazard (PH) model was applied to determine predictors of relapse time among the patients.

  Results: The data showed that 86 clients relapsed into drug use during the treatment program. The proportional hazard assumption was satisfied according to the goodness of fit test showing that Cox proportional hazard model was appropriate. Estimates of the PH model indicated that an increase of 1mg in the methadone dosage could lead to a decrease of 0.15 in hazard ratio and an increase in the length of treatment (p<0.001). Predictors for raising the probability of drug relapse included suffering from mental disorders (compared to mentally healthy: hazard ratio = 2.29, p<0.001), being a poly-substance user (compared to mono-substance users: hazard ratio = 4.80, p<0.001), and having retention experience in the past (compared to those with no previous therapy: hazard ratio = 1.90, p<0.001). Other variables entered in the model, including social and demographic variables, had no statistically significant effect on hazard ratio.

  Conclusions: Although higher methadone dosages are associated with a longer time to relapse, we recommend highly to pay special attention to providing more therapeutic and consultive services to mental health patients, poly-substance users, and individuals with a past therapy record.

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Background and Aim: Gastric cancer is one the most common gastrointestinal tract cancers in Iran, with East-Azerbaijan Province ranking second in the country. The objectives of this research were to determine the feasibility of using cure models in survival analysis and factors affecting short-term and long-term patient survival rates using the mixture cure cox model.

Materials and Methods: We used the available information on 184 patients diagnosed with gastric cancer in East-Azerbaijan Province cities referring to medical centers during the period 2009-2010 and followed up for 5 years.

Results: The median of survival time was 8.33 months (95% CI = 5.9-10.6). Fitting the univariate and final cox cure models showed that in the short-term survival the effect of the chemotherapy factor was statistically significant (Hazard ratio =0.49, 95% CI = 0.34, 0.69, p-value <0.001).

Conclusion: If the population under study consists of two groups of susceptible and non-susceptible individuals for the intended incident, the mixture cure models can be used for the discrete analysis of long-term and short-term survival of patients diagnosed with gastric cancer and identification of variables affecting the two survival rates.