International Journal of Cancer Management
Volume:4 Issue: 1, Winter 2011

Although the Cox proportional hazard regression is the most popular model for analyzing the prognostic factors on survival of cancer patients, under certain circumstances, parametric models estimate the parameter more efficiently than the Cox model. The aim of this study was to compare the Cox regression model with parametric models in patients with gastric cancer who registered at Taleghani hospital, Tehran, Iran. In a retrospective cohort study, 746 patients with gastric cancer were studied from February 2003 through January 2007. Gender, age at diagnosis, distant metastasis, extent of wall penetration, tumor size, histology type, tumor grade, lymph node metastasis and pathologic stage were selected as prognosis, and entered to the models. Lognormal, Exponential, Gompertz, Weibull, Log-logistic and Gamma regression were performed as parametric models, and Akaike Information Criterion (AIC) were used to compare the efficiency of the models. Based on AIC, Log logistic is an efficient model. Log logistic analysis indicated that wall penetration and presence of pathologic distant metastasis were potential risks for death in full and final model analyses. In the multivariate analysis, all the parametric models fit better than Cox with respect to AIC; and the log logistic regression was the best model among them. Therefore, when the proportional hazard assumption does not hold, these models could be used as an alternative and could lead to acceptable conclusions.

During radiotherapy treatment, critical organs are shielded using lead and cerrobend blocks. The objective of this study is to compare the effects of lead and cerrobend shielding blocks on incident photon beam. Collimator scatter factors were measured for open square fields(3 x 3 cm to 40 x 40 cm) defined by collimator jaws and for fields blocked down to smaller asymmetric fields by using five different Lead and Cerrobend blocks for 6 and 15 MV photon beams from a Varian Clinac 2100C accelerator. The measurements in air were performed using Farmer type ionization chamber fitted with acrylic build up caps. The Block Tray Factor (BTF) increased with field size for both 6 and 15 MV photon beams. In case of Lead blocks, the extreme variations in BTF for 6 MV photon beam are 0.70 %, 0.84 %, 0.56%, 0.80 % and 1.15 %. Similarly, for 15 MV the maximum variations for Lead blocks are 0.46 %, 0.60 %, 0.83 %, 0.88 % and 1.10 % respectively. No significant difference has been observed in the BTF of Cerrobend blocks for 6 and 15 MV photon beams. The dose received by a point in air apparently shielded by lead blocks has three main contributions: 1. Due to primary photon beam transmitted through the block, 2. Due to scattered photons, 3. Due to contamination electrons. These three factors collectively cause the increase in BTF with increasing field size, energy, and decreasing block size. The effect of shielding on the beam output increases with field size, beam energy and shield size. This increase follows almost the same pattern for both lead and cerrobend shielding blocks. Therefore shield factors for all field sizes, beam energies and shield sizes should be determined separately for precise patient dose delivery.

To compare the cosmetic results of whole breast radiotherapy between cobalt 60 and photon 9MegaVolt in patients underwent breast conserving surgery. The patients with breast saving surgery who were treated by whole breast radiotherapy with either cobalt 60 or photon 9MV between 2001-2006 in Sayed-al-Shohada hospital entered the study. The cosmetic results were evaluated by an expert radiation oncologist with definite criteria. Frothy patients in cobalt 60 group and 43 patients in photon group were compared, with median follow up of 40.5 months. The patients in photon group had less telangectasia and discoloration (p=0.018 and p=0.01, respectively). The consistency of breast in photon group was better (p=0.019), but for fibrosis the difference was not statistically significant (p=0.055).Overall cosmetic results in photon group was much better rather than cobalt 60 group (p=0.005). No recurrences were observed in both groups. Cosmetic results in group with photon 9MV were superior to cobalt group, but the effect of these two beam energy on disease free survival (DFS) and /or overall survival (OS) should be in more consideration.

Breast cancer is third order malignancy in women among other malignancies. Various studies showed that incidence of breast cancer can be lower down by early detection of breast cancer. Mammographic screening is considered more effective modality in detecting early stage breast cancer in women who are at elevated risk for breast cancer. The aim of this study is to report the results of mammographic screening of women based on the Breast Imaging Reporting and Data System (BI-RADS) for breast cancer. Five hundred four women aged >40 years with no history of breast cancer, no complaints of breast symptoms during any self or clinical examination were underwent breast cancer screening using MAMMOMATE 1000 (Siemens). Descriptive analysis is performed for imaging finding and risk factors. The mean age of 504 women was 51±9.18 years. No family history of breast cancer was present in 418 women (82.9%: 95% CI, 79.4-86.1%). No cancer (negative & benign) was found in 469 women (93.1%: 95% CI, 90.47-95.12%) with R1/R2 scores. For breast imaging scores, 71.62% of all women were R1, 21.42% were R2, 2.38% were R3 while 4.58% were R4 and above. No association (P>0.05) was found between BI-RADS imaging scores and risk factors. In spite of low prevalence of breast cancer in our participants, still there is a need to educate the women at country level about the risk of breast cancer and significance of screening as a tool of early detection of breast cancer.

In medical research, dichotomisation of continuous variables is a widespread use approach. However, it has been argued that dichotomisation might be waste of information. The aim of this paper is to review the main methods to dichotomise continuous data, to address practical issues around dichotomisation methods, and to investigate whether dichotomisation is always a bad idea. A total of 310 breast cancer patients were recruited. Information on 3 categorical and 1 continuous variable (age at diagnosis) was available. Missing data were imputed applying the Multivariable Imputation via Chained Equations (MICE) method. Then a minimum P-value method was applied to dichotomise the age variable. The Cox regression model was fitted to develop models in which dichotomised versus continuous version of the age variable plus other 3 variables were used. Results were compared in terms of discrimination ability, goodness of fit, and classification improvement. For the age variable, an optimal split at 47 was found. This split was close to menopause age of women in Shiraz (48) so had biological interpretability. The stability of optimal split was confirmed in bootstrap study. Model in which dichotomised version of age was used showed higher discrimination ability and goodness of fit. Furthermore, dichotomised model assigned 14% of live patients into a more appropriate risk group. Dichotomisation of continuous data is a contentious issue. We have shown that dichotomisation might improve performance of models when it has biological interpretation. More research is needed to understand situations in which dichotomisation might work.

In Iran colorectal cancer (CRC) incidence varies among various places. But we do not have any validate data that deeply explored the difference of CRC in Kerman province by national average. The aim of this study was to evaluate the incidence of colon cancer within a 12-year period in Kerman province and to find whether the incidence of CRC in Kerman compared with the total incidence found in Iran. Data on colorectal cancer was collected from all histopathology departments around the Kerman Province during 1991 – 2002 retrospectively. The crude and age-standardized incidence rates per 1 million populations were calculated based on the 1996 census data and the population growth rate. During this study total number of 551 new cases of colorectal cancer in Kerman province had been diagnosed. Age Standardized Rate of colon cancer in males and females were 50 (95% CI: 44-56) and 53 (95% CI: 46-59) cases per 1,000,000 population per year, respectively. The risk ratio in females relative to males was not significant in any type of colon cancer. We did not find any difference for each year during the entire study period. The ASR of colorectal cancer in Kerman province was quite lower than the average rate in the whole country. This study showed that, the risk of acquiring colon cancer was constant. We concluded that the risk of colorectal cancer in Kerman province was much lower than the entire country.

Cancer is the third most common cause of death in Iran. Gastric cancer (GC) and colorectal cancer (CRC) are two important causes of mortality due to cancer. With regards to cancer mortality, data are important to monitor the effects of screening program, earlier diagnosis, demographic data and other prognostic factors. The aim of this study was to evaluate the mortality rates and trends from GC and CRC in Iranian population during a period of almost a decade, i.e. from 1995 to 2003. National death Statistic Reported by the Ministry of Health and Medical Education (MOH&ME) from 1995 to 2003, stratified by age group, sex, and cause of death are included in this study. CRC and GC were expressed as the annual mortality rates/100,000, general and/or per gender, and age group. The general mortality rate of CRC slightly increased during the years under study from 0.44 to 2.54 and CRC mortality was higher for older age and male. The general mortality rates of GC showed a sharp increasing from 1.68 to 9.67. In addition to this, GC mortality rate was higher for male than female. Our study indicated remarkable increasing trends in GC and CRC mortality. So developing for a gastric cancer for both primary prevention and early detection programs and manage the delays of diagnosis is recommended to decrease the trend of GC mortality. For CRC, since the rate of CRC screening is very low in Iran, it is recommended that in Iran screening be started as a public program in order to control the mortality and burden of CRC in the future.

Metastases of internal tumors to the oral cavity are unusual and in most cases involve maxilla and mandible. Metastases to the gingival soft tissue are extremely rare. Reporting a new clinical case of renal cell carcinoma (RCC) metastasis with an unusual site. Metastatic involvement of gingival tissue with renal cell carcinoma is an extremely rare clinical event. It is usually associated with involvement of an internal organ. We present a case of 47-year-old male patient diagnosed with RCC-associated gingival metastasis- who underwent radical nephrectomy. The wide range of localizations and forms of metastatic presentation of renal carcinoma should obligate physicians to be alert during the follow-ups.