Further studies on the genetic damage to bone marrow and other somatic effects following exposure to low level tritium

This paper emphasizes results obtained over the last 3 years, supplementing information presented at the first /sup 3/H workshop. Sister chromtid exchange (SCE) measurements on mice maintained on 3.0 ..mu..Ci/ml of tritiated water (HTO) or receiving an equal depth dose /sup 137/Cs gamma exposure for 52 weeks have been completed. Small but significantly higher numbers of SCEs were found in animals receiving gamma exposures or maintained on HTO than in their controls. In animals removed from the HTO regimen after 27 weeks, the number of SCEs decreases with time, but did not return to control levels within the first 30 weeks. Comparative studies with the /sup 137/Cs exposures indicate an RBE not significantly different than 1.0. Mice were also maintained on 7.5, 15.0 and 30.0 ..mu..Ci/ml HTO for SCE studies. Results similar to those described for 3.0 ..mu..Ci/ml were found. Maintaining animals on a 0.15% saccharin solution is the most effective of those tested for increasing the animals' water intake and for enhancing excretion of /sup 3/H. The rate of disappearance of /sup 3/H from animals maintained chronically on HTO indicated a two phase /sup 3/H disappearance curve from hemoglobin. Single injections of HTO showed a brief delay in incorporation of /sup 3/H followed by a disappearance paralleling the slower phase of the chronic exposure curve, and indicating a RBC lifetime of approximately 40 days. 21 references, 7 figures, 1 table

Deep submucosal invasion is not an independent risk factor for lymph node metastasis in T1 colorectal cancer: a meta-analysis

Background & aims: Deep submucosal invasion (DSI) is considered a key risk factor for lymph node metastasis (LNM) and important criterion to recommend surgery in T1 colorectal cancer (CRC). However, metastatic risk for DSI is shown to be low in absence of other histological risk factors. This meta-analysis determines the independent risk of DSI for LNM. Methods: Suitable studies were included to establish LNM-risk for DSI in univariable analysis. To assess DSI as independent risk factor, studies were eligible if 1) risk factors (DSI, poor differentiation (PD), lymphovascular invasion (LVI) and/or high-grade tumor budding (TB)) were simultaneously included in multivariable analysis or 2) LNM-rate of DSI was described in absence of PD, LVI and TB. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. Results: Sixty-seven studies (21,238 patients) were included. Overall LNM-rate was 11.2% and significantly higher for DSI-positive cancers (OR 2.58;95%CI2.10-3.18). Eight studies (3621 patients) were included in multivariable meta-analysis and did not weigh DSI a significant predictor for LNM (OR 1.73;95%CI0.96-3.12). As opposed to a significant association between LNM and PD (OR 2.14;95%CI 1.39-3.28), TB (OR 2.83;95%CI2.06-3.88) and LVI (OR 3.16;95%CI1.88-5.33). Eight studies (1146 patients) analyzed DSI as solitary risk factor: absolute risk of LNM was 2.6% and pooled incidence rate 2.83 (95%CI1.66-4.78). Conclusions: DSI is not a strong independent predictor for LNM and should be reconsidered as a sole indicator for oncologic surgery. The expanding armamentarium for local excision as first-line treatment prompts serious consideration in amenable cases to tailor T1 CRC management