The hypoxic tumour microenvironment, patient selection and hypoxia-modifying treatments

Tumor hypoxia detected by positron emission tomography with 60Cu-ATSM as a predictor of response and survival in patients undergoing Neoadjuvant chemoradiotherapy for rectal carcinoma: a pilot study

PURPOSE

The response of rectal cancers to neoadjuvant chemoradiotherapy is variable. Tumor hypoxia reduces the effectiveness of both radiation therapy and chemotherapy and is a well-known risk factor for tumor radioresistence. We hypothesized that imaging with the novel hypoxia-detecting agent, (60)Cu-diacetyl-bis (N(4)-methylthiosemicarbazone) ((60)Cu-ATSM), previously validated in cervical and lung cancers, would predict the response of rectal cancers to neoadjuvant chemoradiotherapy and prognosis.

METHODS

Patients with locally invasive (T2-4) primary or node-positive rectal cancer located <12 cm from the anal verge were recruited for this pilot study. Pretreatment tumor size and stage were determined by endorectal ultrasonography, CT, and magnetic resonance imaging. Eleven patients also underwent clinical positron emission tomography with (18)F-fluorodeoxyglucose at the discretion of the treating clinician. The primary tumor was imaged by positron emission tomography with (60)Cu-ATSM, and accumulation of the tracer was measured semiquantitatively by determining the tumor-to-muscle activity ratio. Neoadjuvant chemoradiotherapy was then administered (within 2 weeks of (60)Cu-ATSM-positron emission tomography) and consisted of 45 Gy given in 25 fractions to the pelvis with continuous intravenous infusion of 5-fluorouracil (225 mg/m(2)/day). Proctectomy was performed six to eight weeks after neoadjuvant chemoradiotherapy and the tumor submitted to pathology for size measurement and staging. Tumor-to-muscle activity ratios were compared with tumor (18)F-fluorodeoxyglucose uptake, tumor response to neoadjuvant chemoradiotherapy, and with patient survival.

RESULTS

Nineteen patients were enrolled in the study, two of whom were excluded from final analysis (1 death during neoadjuvant chemoradiotherapy and 1 tumor perforation during neoadjuvant chemoradiotherapy requiring emergent surgery). Of the 17 remaining patients, 14 had a reduction in tumor size and 13 were downstaged. The median tumor-to-muscle activity ratio of 2.6 discriminated those with worse prognosis from those with better prognosis. Both overall and progression-free survivals were worse with hypoxic tumors (tumor-to-muscle activity ratio >2.6) than with nonhypoxic tumors (tumor-to-muscle activity ratio <or=2.6; both P < 0.05). In addition, 2 of the 3 tumors with no change in size had tumor-to-muscle activity ratios >2.6 (positive predictive value 66 percent), whereas 6 of 14 with decreased size had tumor-to-muscle activity ratios >2.6 (negative predictive value 57 percent). Three of the 4 tumors not downstaged had tumor-to-muscle activity ratios >2.6 (positive predictive value 75 percent), whereas 5 of 13 downstaged tumors had tumor-to-muscle activity ratios >2.6 (negative predictive value 62 percent). The mean tumor-to-muscle activity ratio for downstaged tumors (2.2) was significantly lower than that of nondownstaged tumors (3.3) (P = 0.03). The difference in mean tumor-to-muscle activity ratio between downsized (2.3) and nondownsized (2.9) tumors did not reach statistical significance (P = 0.36). Tumor (18)F-fluorodeoxyglucose uptake (n = 11) did not correlate with (60)Cu-ATSM uptake (r = 0.4; P = 0.9) and there was no significant difference in mean tumor (18)F-fluorodeoxyglucose uptake between patients with hypoxic tumors and those with normoxic tumors (P = 0.3).

CONCLUSIONS

The results of this small pilot study suggest that (60)Cu-ATSM-PET may be predictive of survival and, possibly, tumor response to neoadjuvant chemoradiotherapy in patients with rectal cancer. A larger Phase II study is warranted to validate these results.

No detectable hypoxia in malignant salivary gland tumors: preliminary results

PURPOSE

Hypoxia is detected in most solid tumors and is associated with malignant progression and adverse treatment outcomes. However, the oxygenation status of malignant salivary gland tumors has not been previously studied. The aim of this study was to investigate the potential clinical relevance of hypoxia in this tumor type.

METHODS AND MATERIALS

Twelve patients scheduled for surgical resection of a salivary gland tumor were preoperatively injected with the hypoxia marker pimonidazole and the proliferation marker iododeoxyuridine. Tissue samples of the dissected tumor were immunohistochemically stained for blood vessels, pimonidazole, carbonic anhydrase-IX, glucose transporters-1 and -3 (Glut-1, Glut-3), hypoxia-inducible factor-1alpha, iododeoxyuridine, and epidermal growth factor receptor. The tissue sections were quantitatively assessed by computerized image analysis.

RESULTS

The tissue material from 8 patients was of sufficient quality for quantitative analysis. All tumors were negative for pimonidazole binding, as well as for carbonic anhydrase-IX, Glut-1, Glut-3, and hypoxia-inducible factor-1alpha. The vascular density was high, with a median value of 285 mm(-2) (range, 209-546). The iododeoxyuridine-labeling index varied from <0.1% to 12.2% (median, 2.2%). Epidermal growth factor receptor expression levels were mostly moderate to high. In one-half of the cases, nuclear expression of epidermal growth factor receptor was observed.

CONCLUSION

The absence of detectable pimonidazole binding, as well as the lack of expression of hypoxia-associated proteins in all tumors, indicates that malignant salivary gland tumors are generally well oxygenated. It is unlikely that hypoxia is a relevant factor for their clinical behavior and treatment responsiveness.

Wound healing in radiated skin: pathophysiology and treatment options

Ulcers in radiated skin continue to be a challenge for health care practitioners. Healing impairment in the setting of radiation-damaged tissue will most of the time lead to chronic wounds that reduce the patient's quality of life. In this review, we present an update of the pathophysiology of tissue damage caused by radiation that leads to chronic ulceration. We also explore the evidence available on the different prevention and treatment modalities that have been reported in the literature. The evidence for most preventive measures is inconclusive; however, sucralfate and amifostine seem to be the adequate recommendations for prophylaxis. As for treatment of ulcerated patients, the strongest level of evidence found was for the use of pentoxifylline, but proper trials are still scarce to be considered standard adjuvant therapy. Hyperbaric oxygen, cytokines and other growth factors and surgical interventions have shown some benefit in case reports and case series only. Other therapies show promise based on their mechanism of action but need to be tested in human studies and clinical trials.

Hypoxia environment and gastric cancer

Tumor hypoxia is a characteristic in many solid tumors. It has been demonstrated that hypoxia in gastric cancer could promote tumor microvessels angiogenesis, affect tumor cell apoptosis, regulate cell cycle, decrease the therapeutic efficacy of radiotherapy, surgery and some forms of chemotherapy, and promote tumor invasion and metastasis. Using oxygen electrodes, radiological and nuclear medical imaging techniques we could assess the tumor oxygenation status. The use of hyperbaric oxygen, carbogen and ARCON and hypoxic cell radiosensitisers can improve the efficacy of radiation and chemotherapy. Hypoxia environment indicates several new methods to treat gastric cancer, and the exogenous markers of tumor hypoxia, HIF-1 inhibitor, and HIF-1 gene therapy will be the focus in the future.