Study Using Fluorine-18-Labeled Fluoro-Misonidazole Positron Emission Tomography to Detect Hypoxia in Locally Advanced (T3-T4 and./or N1)Primary Rectal Cancer Patients

Study Using Fluorine-18-Labeled Fluoro-Misonidazole Positron Emission Tomography to Detect Hypoxia in Locally Advanced (T3-T4 and./or N1)Primary Rectal Cancer Patients

A Feasibility Study Using Fluorine-18-Labeled Fluoro-Misonidazole Positron Emission Tomography to Detect Hypoxia in Locally Advanced (T3-T4 and./or N1)Primary Rectal Cancer Patients

When used with a different radioactive tracer called FMISO, a PET scan can find areas of low oxygen in the tumor. We think that having areas of low oxygen is a reason why some tumors are hard to treat with radiation. In a past study, FMISO PET scans were performed in 6 patients with rectal cancer that could not be operated on and that had spread to other areas. In this group of patients, FMISO PET scans were able to find the low oxygen areas in their tumors. But this study included only a few patients. In the present study, we want to use FMISO PET scans in patients who have tumors that can be operated on. This group of patients will have radiation, chemotherapy or both before they have their surgery. We want to see if FMISO PET can find low oxygen areas in this distinct group of patients.

Hypoxia is a characteristic feature of malignant solid tumors associated with poor prognosis and resistance to chemotherapy and radiation. It has also been shown (6) that the presence of hypoxia may reduce long-term survival post surgery. Hypoxia renders tumor cells up to three times more resistant to ionizing radiation than aerobic cells. The presence of hypoxic regions within tumors may be one factor leading to local failure after treatment with standard pre-operative radiotherapy doses. If these regions could be identified and verified using a non-invasive imaging technique prior to surgery, they could be specifically targeted using sophisticated planning techniques such as intensity modulated radiation therapy (IMRT) to deliver higher doses ionizing radiation with preoperative radiotherapy. Future studies using IMRT to "dose paint" areas of hypoxia within tumors will build upon the results of this feasibility study. Ultimately, by the delivery of differential dose of radiation to the tumor, in combination with surgery, the local control rates of rectal cancer patients may further be improved.

You will be scanned 2 to 3 times on the same day, but you will only be administered one dose of the FMISO tracer. The first scan will last about 30 minutes. Then you will have 1 to 3 hours to wait before you are scanned again. Some patients will undergo a second scan approximately one-and-a-half hours after the start of the first scan. This scan will last about 10 minutes. The final scan will occur between 2-4 hours after the start of the first scan. This final scan will also last about 10 minutes. During the PET scan, you may have a separate i.v. line put into your other arm so that we can take 2 to 3 blood samples. These samples will be less than half a teaspoon each. We are taking these blood samples to see how quickly FMISO leaves your blood stream. The first sample will be taken between 2 and 40 minutes after the FMISO is injected. The other two blood samples will be taken with each subsequent scan.

the feasibility of a non-invasive method of detecting hypoxia, using F-FMISO-PET imaging in colorectal cancer patients.

determine volume of hypoxic tumor ROIs as a proportion of the entire tumor volume by this non-invasive imaging technique. ROIs are defined as those voxels, within the tumor volume defined on FDG PET/CT, for which the 18F-F-FMISO radioactivity concent

prior to F-FMISO injection, btw 2-40 min post injection, (ii) btw 80-100 min post injection & (iii) btw 110- 140 min post injection. Btw 1 & 3 cc of blood will be taken at each time point (making the max volume of blood withdrawn during this study < 9 cc

Inclusion Criteria: Able to provide written informed consent Histologically confirmed diagnosis of Stage 2 or Stage 3 rectal carcinoma requiring preoperative radiation, chemotherapy or both, per treating physician 18 years of age or older Karnofsky performance status ≥ or = to 70 Exclusion Criteria: Women who are pregnant (confirmed by serum b-HCG in women of reproductive age) or breast feeding