Status of radiotherapy]

Increasing toxicity during neoadjuvant radiochemotherapy as positive prognostic factor for patients with esophageal carcinoma

The aim of this study was to correlate acute organ toxicity during preoperative radiochemotherapy with overall survival and tumor regression for patients with primarily operable esophageal carcinoma. From 1995 to 2002, 60 patients with primarily operable esophageal carcinoma were treated in a preoperative setting at our department. Thirty-three percent of the patients had International Union against Cancer (UICC)-stage II tumors, 62% had UICC-stage III tumors, and 5% had UICC-stage IVA tumors. All patients received irradiation (40 Gy at 2 Gy/fraction). Chemotherapy for all patients with adenocarcinoma and, from 2001, also for patients with squamous cell carcinoma consisted of two cycles, 5-fluorouracil and cisplatinum; between 1995 and 2001, patients with squamous cell carcinoma received three courses of chemotherapy (folinic acid, etoposide, 5-fluorouracil, and cisplatinum every 3 weeks) before and further cisplatinum and etoposide during radiotherapy. We found a significant correlation between acute organ toxicity and histopathological tumor regression, as well as overall survival. The probability to achieve tumor regression grade 1 after radiochemotherapy was nearly four times higher for patients with worsening of odynophagia than for those without an increase (odds ratio: 3.97). Patients with worsening of odynophagia had a 5-year overall-survival rate of 66% compared with 39% in patients without (P = 0.048). Our data indicate that normal tissue and tumor tissue may behave similar with respect to treatment response, as acute organ toxicity showed to be an independent prognostic marker in our patient population. The hypothesis should be further analyzed on biomolecular and clinical level in future clinical trials.

[Modern diagnostics and stage-oriented surgery: therapy of adenocarcinoma of the esophagogastric junction]

The basis for decision-making about an individualized surgical treatment of adenocarcinoma of the esophagogastric junction is tumor staging and exact evaluation of the topography of the tumor in the small junctional area. The diagnostics mainly comprise endoscopy, biopsy, endosonography, computed tomography and partially diagnostic laparoscopy. This results in a clinical TNM staging and an evaluation according to the AEG classification from oral to aboral in type I (esophagus), type II (cardia) and type III (subcardia). Endoscopic resection is only appropriate for the infrequent mucosal carcinomas whereas the majority of the junctional carcinomas are treated by surgical resection. This is combined with neoadjuvant treatment in case of T3 or resectable T4 carcinomas. A type I carcinoma is removed by radical transthoracic en bloc esophagectomy with high intrathoracic esophagogastrostomy after gastric pull-up. In case of type II or III carcinomas, a transhiatal extended gastrectomy including distal esophageal resection is performed with reconstruction by Roux en Y esophagojejunostomy in the lower mediastinum. However, some advanced type II carcinomas which cannot be resected R0 at the esophagus need esophagectomy and gastric pull-up. This surgical strategy is justified by the topography of the lesion and the corresponding lymphatic drainage. Very rare indications are seen for a limited resection with interposition of small bowel in some mucosal carcinomas or total esophagogastrectomy with colon interposition in very advanced tumors. The neoadjuvant treatment comprises especially chemoradiation for type I and chemotherapy for type II and III carcinomas and leads to a significant survival benefit compared to surgery alone.

Radiation sensitivity of esophageal adenocarcinoma: the contribution of the RNA-binding protein RNPC1 and p21-mediated cell cycle arrest to radioresistance

Radiation combined with chemotherapy (neo-CRT) is increasingly the standard of care for the treatment of esophageal cancer, either as neoadjuvant therapy in multimodal protocols or as primary therapy. Unfortunately, ~60% of patients demonstrate little or no response to neo-CRT. Accordingly, understanding the molecular mechanisms of resistance to therapy may underpin significant advances through the identification of nonresponders either before or early in treatment. We previously identified the RNPC1 gene, which is important in stabilizing p21, as being upregulated in the tumors of esophageal cancer patients who had a poor response to neo-CRT. We hypothesize that RNPC1 contributes to resistance to radiation therapy through a p21-mediated cell cycle accumulation/arrest mechanism. Analysis revealed that p53 and RNPC1 expression were highest in the JH-EsoAd1 cell line and lowest in OE19 cells. This was associated with accumulation of cells in G₀/G₁. p21 expression, which was highest in OE19 cells and lowest in OE33 cells, was associated with relative intrinsic sensitivity to radiation. OE33 cells were transfected with a plasmid (pCMV6-AC-GFP) encoding a C-terminal GFP-tagged RNPC1, and overexpression was confirmed by qPCR and fluorescence microscopy. Overexpression of RNPC1-GFP resulted in significantly increased levels of the p21 transcript and protein through a direct physical interaction between the RNPC1 protein and the p21 transcript. Furthermore, RNPC1 overexpression led to significant G₀/G₁ cell cycle accumulation and significantly enhanced cellular resistance to radiation. We conclude that RNPC1 contributes to tumor resistance to radiotherapy, which likely occurs through a p21-mediated G₀/G₁ accumulation mechanism. Therefore, RNPC1 may represent a potential therapeutic target for enhancing tumor sensitivity to radiation.

Choosing the best treatment for esophageal cancer : criteria for selecting the best multimodal therapy

The best multimodal therapy in esophageal cancer comprises neoadjuvant radiochemotherapy in patients with adenocarcinoma or squamous cell carcinoma whereas neoadjuvant chemotherapy is only appropriate for patients with adenocarcinoma. However, the 2-year survival benefit by this induction therapy compared to surgery alone is only 5-9 %. Targeted drugs seem to be promising in order to improve the response rate. The choice of the best multimodal therapy by response prediction seems only to be possible in patients during chemotherapy for adenocarcinoma, whereas during neoadjuvant radiochemotherapy a response prediction by FDG-PET is not possible. The principle item of multimodal therapy is still transthoracic en bloc esophagectomy which should be performed in high volume centers in order to guarantee stable and good results.