BackgroundMediterranean societies, with diets rich in vitamin E isoforms, have a lower risk for colon cancer than those of northern Europe and the Americas. Vitamin E rich diets may neutralize free radicals generated by fecal bacteria in the gut and prevent DNA damage, but signal transduction activities can occur independent of the antioxidant function. The term vitamin E represents eight structurally related compounds, each differing in their potency and mechanisms of chemoprevention. The RRR-γ-tocopherol isoform is found primarily in the US diet, while RRR-α-tocopherol is highest in the plasma.MethodsThe effectiveness of RRR-α- and RRR-γ-tocopherol at inhibiting cell growth and inducing apoptosis in colon cancer cell lines with varying molecular characteristics (SW480, HCT-15, HCT-116 and HT-29) and primary colon cells (CCD-112CoN, nontransformed normal phenotype) was studied. Colon cells were treated with and without RRR-α- or RRR-γ-tocopherol using varying tocopherol concentrations and time intervals. Cell proliferation and apoptosis were measured using the trypan blue assay, annexin V staining, DNA laddering and caspase activation.ResultsTreatment with RRR-γ-tocopherol resulted in significant cell death for all cancer cell lines tested, while RRR-α-tocopherol did not. Further, RRR-γ-tocopherol treatment showed no cytotoxicity to normal colon cells CCD-112CoN at the highest concentration and time point tested. RRR-γ-tocopherol treatment resulted in cleavage of PARP, caspase 3, 7, and 8, but not caspase 9. Differences in the percentage cell death and apoptosis were observed in different cell lines suggesting that molecular differences in these cell lines may influence the ability of RRR-γ-tocopherol to induce cell death.ConclusionThis is the first study to demonstrate that multiple colon cancer cell lines containing varying genetic alterations will under go growth reduction and apoptosis in the presence of RRR-γ-tocopherol without damage to normal colon cells. The amount growth reduction was dependent upon the molecular signatures of the cell lines. Since RRR-γ-tocopherol is effective at inhibition of cell proliferation at both physiological and pharmacological concentrations dietary RRR-γ-tocopherol may be chemopreventive, while pharmacological concentrations of RRR-γ-tocopherol may aid chemotherapy without toxic effects to normal cells demonstrated by most chemotherapeutic agents.

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Purpose Toxicity concerns have limited pelvic nodal prescriptions to doses that may be suboptimal for controlling microscopic disease. In a prospective trial, we tested whether image-guided IMRT can safely deliver escalated nodal doses while treating the prostate with hypofractionated radiotherapy in 5–1/2 weeks. Methods and Materials Pelvic nodal and prostatic image-guided IMRT was delivered to 53 NCCN high risk patients to a nodal dose of 56 Gy in 2 Gy fractions with concomitant treatment of the prostate to 70 Gy in 28 fractions of 2.5 Gy, and 50 of 53 patients received androgen deprivation for a median duration of 12 months. Results The median follow-up was 25.4 months (range 4.2–57.2). No early grade 3 (Gr3) RTOG or CTCAE v.3.0 GU or GI toxicities were seen. The cumulative actuarial incidence of Gr2 early GU toxicity (primarily alpha blocker initiation) was 38%. The rate was 32% for Gr2 early GI toxicity. None of the dose-volume descriptors correlated with GU toxicity, and only the volume of bowel receiving ≥30 Gy correlated with early GI toxicity (p=0.029). Maximum late grades 1,2 and 3 GU toxicities were seen in in 30%, 25% and 2%, respectively. Maximum late grade 1 and 2 GI toxicities were seen in 30% and 8% (rectal bleeding requiring cautery), respectively. The estimated 3-year biochemical control (nadir + 2) was 81.2 ± 6.6%. No patient manifested pelvic nodal failure, while two experienced para-aortic nodal failure outside the field. The 6 other clinical failures were distant only. Conclusions Pelvic IMRT nodal dose escalation to 56 Gy was delivered concurrently with 70 Gy of hypofractionated prostate radiotherapy in a convenient, resource-efficient and well-tolerated 28 fraction schedule. Pelvic nodal dose escalation may be an option in any future exploration of potential benefits of pelvic radiation therapy in high-risk prostate cancer patients.

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Whole pelvic radiotherapy with concurrent chemotherapy is the standard of care for locally advanced cervical carcinoma. Published literature reports that the pelvic bone marrow (BM) dosimetric parameters of V10  90% and V20  80% are associated with higher rates of hematologic toxicities using this approach. Here, we investigate the ability of Tomotherapy based intensity modulated radiation therapy (IMRT) to reduce dose to pelvic BM while evaluating dose distribution to critical structures and planning target volume (PTV) coverage. Ten patients were selected for analysis. Normal structures, whole pelvic BM, PTV contours, and IMRT objects were standardized. Two whole pelvis Tomotherapy plans were created for each patient, one standard plan, and one with the addition of a BM sparing (BMS) constraint (V10  85%, V20  80%). Data were calculated from multiple points with regard to BM dose, normal structure dose, and PTV coverage. Differences in dose distributions between the two sets of plans were analyzed using a paired t-test. The addition of a BMS planning constraint resulted in significant decreases in pelvic BM dose at the following dosimetric points: V5, V10, V15, V20, V30, V40, V50, and mean dose (p  0.05 for all points). There were no significant differences in dose to small bowel, bladder or rectum, with the exception of one data point (small bowel V30, p 5 0.004) between the two sets of plans. There was no sacrifice of PTV coverage or loss of homogeneity with the addition of a BMS planning constraint. BMS-IMRT significantly reduces radiation dose to the pelvic BM while maintaining the ability to spare dose to the small bowel, bladder and rectum. The planning constraints were met without violation of study criteria, and without sacrifice of PTV coverage. Further investigation is warranted to determine if rates of hematologic toxicity improve with utilization of Tomotherapy based BMS-IMRT.