What about sentinel lymph node biopsy for early breast cancer during pregnancy?

Pregnancy-associated breast cancer is rare, but this clinical situation arises in 1/10,000-1/3000 pregnancies. In patients presenting an early-stage breast tumor devoid of clinically pathological lymph node, sentinel lymph node (SLN) biopsy has not yet been validated as a routine procedure for pregnant women due to the lack of data in the literature. The blue dye injection is not recommended because of 2% theoretical risk of anaphylactic shock. Several studies have shown that Tc99m injection at conventional dose between 12.1 and 18.5MBq exposed the fetus to an irradiation between 0.011 and 0.0245mSv much below the 50mSv recommended threshold. As evidenced by lymphoscintigraphy scans, the dose of injected Tc99m is localized at the injection site and in the SLN. According to the literature, the SLN technique does not seem to impact the fetal or obstetrical prognosis. Studies involving larger cohorts are required to confirm these data and to indicate this technique in pregnant women. Considering the benefit for the patient and the low risk incurred on both fetal and obstetrical levels, it appears reasonable to discuss the indication of SLN on a case-by-case basis in multidisciplinary oncologic meetings.

Chest X-ray Artifact Caused by Bilateral 99mTc-Antimony Trisulfite Injection for Sentinel Node Imaging in a Patient With Breast Cancer.

A 52-year-old woman diagnosed with invasive ductal carcinoma of both breasts had a chest x-ray for preoperative assessment. A striking artifact was noted by the x-ray technologist, who, as a result, became very concerned about radiation exposure from the patient. The patient had undergone bilateral sentinel lymph node injections in the nuclear medicine department with Tc-antimony trisulfite colloid just 2 hours before the chest x-ray. Radiation exposure to the x-ray technologist was determined to be similar to 8 hours of naturally occurring background radiation (∼2.96 µSv).

Is technetium-99 (Tc-99) radiologically significant?

According to radiological protection authorities the radioisotope technetium-99 (Tc-99) is not 'radiologically significant' to humans or other species. The Sellafield plutonium reprocessing plant discharges large amounts of Tc-99 into the Irish Sea; by the year 2015 a total of about 3,000 tera-becquerels of Tc-99, weighing about 5 tonnes, will have been discharged. This article considers the effects of Tc-99 on the environment. After discharge, Tc-99 travels large distances in the ocean. Levels of Tc-99 in Norwegian coastal waters increased by ten times between 1991 and 1996. Tc-99 becomes concentrated offshore in seaweed, winkles and mussels. A concentration factor of 120,000 has been reported in seaweed and one of 650,000 has been measured in the green gland of lobster. It may be necessary to reassess the risk to human health following the ingestion of the relevant isotopes, including Tc-99, because of the possibility of radiation induced genomic instability, as well as the cancer risk. The committed effective doses used to determine permitted levels of intake of these isotopes should be increased and the authorized limits for the discharge of radioactive wastes from Sellafield reduced. Authorized limits of the discharge of radioactivity should be based on Contaminated Food Intervention Levels rather than Generalized Derived Limits as they are now.

The safety and pharmacokinetics in adult subjects of an intravenously administered 99mTc-labeled 17 amino acid peptide (CYT-379).

A phase I study was designed to evaluate the safety and pharmacokinetics of a novel platelet reactive peptide, peptide acetyl-SYGRGDVRGDFKCTCCA-amide (CYT-379), which binds to the fibrinogen receptor of activated platelets and also binds to 99mTc. Eleven subjects with suspected deep venous thrombosis had 0.1, 0.5 or 1.0 mg of the peptide infused intravenously. Pharmacokinetics were determined by assaying blood samples in 6 of the 11 subjects and by urine sampling in 5 of these 6 subjects. Plasma and whole blood time-activity curves demonstrated an initial fast component with half-time clearance of 0.2 +/- 0.01 and 0.2 +/- 0.02 h and a slow component with half-time clearance of 2.8 +/- 0.3 and 2.7 +/- 0.2 h (mean +/- SEM for plasma and whole blood, respectively). Urine clearance was 22.6 +/- 3.3 and 10.8 +/- 1.6 mL/min when normalized to body surface area. The cumulative excretion of 99mTc-CYT-379 in the urine was 16.6 +/- 3.6, 45.6 +/- 16.9 and 45.6 +/- 1.8% of the administered dose over 0-2, 0-12 and 0-24 h after radiopharmaceutical injection, respectively. Images obtained in 11 subjects immediately, at 1-2, and 4-6 h after injection were evaluated for abnormalities and were compared with duplex Doppler ultrasonography. 99mTc-CYT-379 images were positive in only 3 of 7 subjects who had a positive duplex Doppler examination in at least one lower extremity. One subject with negative duplex Doppler had also negative 99mTc-CYT-379 scintigraphy. One subject with negative scintigraphy and two other subjects with positive scintigraphy had no other imaging studies of the deep venous system performed. No adverse reactions were observed during or after the infusion of 99mTc-CYT-379. 99mTc-CYT-379 appears to be a safe radiopharmaceutical and demonstrates rapid clearance from plasma in human subjects.