Evidence based radiation oncology with existing technology. Rep Pract Oncol Radiother. 2014;19:259-266. [PMID: 25061519 DOI: 10.1016/j.rpor.2013.09.002]

Efficacy and safety of intensity-modulated radiation therapy versus three-dimensional conformal radiation treatment for patients with gastric cancer: a systematic review and meta-analysis

BACKGROUND

Radiation or radiochemotherapy is a common adjuvant therapy for gastric cancer. Intensity-modulated radiation therapy (IMRT) has been demonstrated to provide better dose conformity, allowing dose escalation and/or reduction of normal tissue exposure compared with three-dimensional conformal radiation treatment (3D-CRT). However, the efficacy of IMRT and 3D-CRT in gastric cancer remains controversial. This study aimed to compare the efficacy and safety of IMRT with those of 3D-CRT in treating patients with gastric cancer through conducting a meta-analysis of 3-year survival rates [overall survival (OS) and disease-free survival (DFS)], local control rates, and toxic event rates.

METHODS

Embase, PubMed, the Cochrane Library, and clinical trial databases were searched to identify the clinical trials of IMRT versus 3D-CRT for treating patients with gastric cancer. The obtained data of survival and safety were analyzed using the Stata 14.0 software.

RESULTS

A total of 9 controlled clinical studies, including 516 patients with gastric cancer, met the inclusion criteria and were included in this meta-analysis. The results of the meta-analysis showed that the 3-year OS rate was slightly higher in the IMRT group than in the 3D-CRT group, without any statistical significance. The 3-year local control rate was significantly higher in the IMRT group than in the 3D-CRT group. No significant difference in the 3-year DFS rate was found between the IMRT and 3D-CRT groups. Grade 2-4 toxicities were similar between the IMRT and 3D-CRT groups.

CONCLUSION

The findings suggested that IMRT might be superior to 3D-CRT in treating patients with gastric cancer in terms of local control rates without increasing toxicity.

KRAS Mutation in Gastric Cancer and Prognostication Associated with Microsatellite Instability Status

Microsatellite instability (MSI) is one of the subgroups based on the new molecular classification of gastric cancer (GC). In this study, we analyzed the role of KRAS status in MSI GC and the impact of MSI status on KRAS mutation. We performed analysis on 595 GC patients. Polymerase chain reaction (PCR) was used for the screening of KRAS mutation (exon 2) and 5 quasi-monomorphic mononucleotide repeats, namely, BAT-26, BAT-25, NR -24, NR-21, and NR-27 were used to determine the MSI status. The KRAS and MSI status were then compared with clinicopathologic data of the GC patients. MSI GC was found in 20.3% of all cases. KRAS mutation was seen in 24 patients; 18 were MSI (75%) and 6 were microsatellite stable (MSS) (25%). MSI GC patients with KRAS mutation were older and mostly female, but MSS presented more advanced T and N stage of the disease, more cardia tumors, and adjuvant treatment. Five-year survival was 72.2% for KRAS mutation patients with MSI and 0% for MSS (p < 0.001). Although KRAS mutations in GC are linked with MSI in the majority of cases, KRAS mutations with MSS status presented with a poor prognosis and a worse outcome. In multivariate analysis, MSI was associated with better survival (p < 0.001) but KRAS was with worse survival (p = 0.304). Our study suggests that KRAS mutations are based on MSI status rather than different codon subtypes of mutation, and such a division could be used to determine the GC patient outcome.

Familial aggregation of gastric cancer with microsatellite instability

BACKGROUND

Microsatellite instability (MSI) is currently a new molecular subtype of gastric cancer (GC). About 90% of GC cases appear sporadically. MSI seems to be responsible for both sporadic and familial GC. The aim of this study was to analyze the frequency of MSI in GC with familial history of GC.

METHODS

The MSI analysis was conducted using five quasi-monomorphic mononucleotide repeats: BAT-26, BAT-25, NR-24, NR-21 and NR-27. From our database, we analyzed 457 patients in terms of cancer history across family members, particularly focusing on GC.

RESULTS

MSI status in patients without familial history of GC was present in 22.1% of the cases, whereas in the patients with familial history of GC it was present in 28% of the cases (p = 0.220). For 1st or 2nd degree family members with GC, MSI was observed in 27.6% and in 30.8%, respectively (p = 0.812). MSI was observed in hereditary gastric cancer (HGC) in 33.3% and in familial gastric cancer (FGC) in 30%. No difference in survival rates was observed between the analyzed groups.

CONCLUSIONS

In our publication, we could not find any link between familial background and the MSI status in GC patients. More detailed molecular and genetic analysis of subgroups of these patients is required.

High-risk and low-risk gastric cancer areas in Italy and its association with microsatellite instability

PURPOSE

The different pathological characteristics and prognoses between gastric cancer patients coming from high-risk (group A) and low-risk (group B) areas of Italy were analyzed. We investigated a suspected difference in microsatellite instability (MSI) between these two groups.

METHODS

MSI analyses of 452 gastric cancer patients were performed using five quasimonomorphic mononucleotide repeats NR-21, NR-24, NR-27, BAT-25, and BAT-26. MSI analysis was done by PCR usage. An allelic profile of these five mononucleotides was detected on an automated DNA sequencer ABI PRISM 3100 Genetic Analyser. Data were analyzed according to high-risk and low-risk gastric cancer areas.

RESULTS

MSI was observed in 23.9 % of all gastric cancer patients studied. Patients from group A showed a higher rate of MSI (28.4 %) than from group B (13.5 %) (p < 0.001). We analyzed this association together with tumor location and Lauren classification: A nonsignificant differences were seen when analyzing cardia and non-cardia tumors (p = 0.854) but significant for Lauren histotype (p = 0.028). There was no statistical difference in survival between high-risk and low-risk areas (p = 0.437), with a nonsignificant trend for better survival in the high-risk group, especially when measured over a longer period of time. Analyzing MSI or MSS in these groups, the survival curves were almost the same.

CONCLUSIONS

A higher frequency of MSI in patients coming from high-risk areas may help explain geographical differences in gastric cancer. The trend of better survival in high-risk areas may be due to a higher rate of MSI gastric cancer patients.

Treatment of limited-stage small cell lung cancer in the elderly, chemotherapy vs. sequential chemoradiotherapy vs. concurrent chemoradiotherapy: that's the question

Chemotherapy is the mainstay of the treatment in limited disease (LD) and extended disease (ED) small cell lung cancer (SCLC) patients, while concurrent chemoradiotherapy (CRT) is the standard of care in healthy patients with LD. However, this intensive treatment is associated with significantly more toxicity in the subset of patients aged 70 years or more. To date, most of available data concerning CRT in elderly derived from retrospective analyzes, usually conducted on small samples of patients, poorly representative of this population. Modern CRT appears to confer a survival benefit compared to chemotherapy alone in a recent retrospective analysis conducted on elderly patients with LD-SCLC. Age alone should not be a contraindication for multimodality treatment in this subset of patients.

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for treatment of ovarian cancer

Hyperthermic intraperitoneal chemotherapy (HIPEC), a strategy combining maximal cytoreductive surgery and maximal regional chemotherapy, has been applied to treat ovarian cancer resulting in long-term survival rates in selected patients. However, the status of HIPEC in ovarian cancer remains an experimental procedure, given the many variables among the data and trials reviewed, to enable us to derive strong conclusions about its role from this overview. In this review we discuss treatment with HIPEC in patients with ovarian cancer and future prospective of its use in clinical setting. HIPEC is an effective tool in the treatment of selected patients with peritoneal carcinomatosis from ovarian cancer. Unfortunately, due to the lack of randomised trials, the evidence of HIPEC is very limited. Future randomised studies are awaited to define the role and clinical impact of HIPEC in ovarian cancer.

Gastric cancer: Current status of lymph node dissection

D2 procedure has been accepted in Far East as the standard treatment for both early (EGC) and advanced gastric cancer (AGC) for many decades. Recently EGC has been successfully treated with endoscopy by endoscopic mucosal resection or endoscopic submucosal dissection, when restricted or extended Gotoda's criteria can be applied and D1+ surgery is offered only to patients not fitted for less invasive treatment. Furthermore, two randomised controlled trials (RCTs) have been demonstrating the non inferiority of minimally invasive technique as compared to standard open surgery for the treatment of early cases and recently the feasibility of adequate D1+ dissection has been demonstrated also for the robot assisted technique. In case of AGC the debate on the extent of nodal dissection has been open for many decades. While D2 gastrectomy was performed as the standard procedure in eastern countries, mostly based on observational and retrospective studies, in the west the Medical Research Council (MRC), Dutch and Italian RCTs have been conducted to show a survival benefit of D2 over D1 with evidence based medicine. Unfortunately both the MRC and the Dutch trials failed to show a survival benefit after the D2 procedure, mostly due to the significant increase of postoperative morbidity and mortality, which was referred to splenopancreatectomy. Only 15 years after the conclusion of its accrual, the Dutch trial could report a significant decrease of recurrence after D2 procedure. Recently the long term survival analysis of the Italian RCT could demonstrate a benefit for patients with positive nodes treated with D2 gastrectomy without splenopancreatectomy. As nowadays also in western countries D2 procedure can be done safely with pancreas preserving technique and without preventive splenectomy, it has been suggested in several national guidelines as the recommended procedure for patients with AGC.

The concept of radiation-enhanced stem cell differentiation

BACKGROUND

Efficient stem cell differentiation is considered to be the holy grail of regenerative medicine. Pursuing the most productive method of directed differentiation has been the subject of numerous studies, resulting in the development of many effective protocols. However, the necessity for further improvement in differentiation efficiency remains. This review contains a description of molecular processes underlying the response of stem cells to ionizing radiation, indicating its potential application in differentiation procedures. In the first part, the radiation-induced damage response in various types of stem cells is described. Second, the role of the p53 protein in embryonic and adult stem cells is highlighted. Last, the hypothesis on the mitochondrial involvement in stem cell development including its response to ionizing radiation is presented.

CONCLUSIONS

In summary, despite the many threats of ionizing radiation concerning genomic instability, subjecting cells to the appropriate dosage of ionizing radiation may become a useful method for enhancing directed differentiation in certain stem cell types.