The safety of lymphatic mapping in pregnant breast cancer patients using Tc-99m sulfur colloid

Breast J. 2004 Nov-Dec;10(6):492-5. doi: 10.1111/j.1075-122X.2004.21503.x.


This investigation was undertaken to assess the risk to the embryo/fetus associated with sentinel lymph node biopsy and lymphoscintigraphy of the breast performed in pregnant patients. Approximately 92.5 MBq (2.5 mCi) of filtered Tc-99m sulfur colloid was injected peritumorally the day before surgery in two nonpregnant women with breast cancer. The whole-body distribution of the radiopharmaceutical was evaluated using a gamma camera 1 hour after injection. We then calculated the absorbed dose to the embryo/fetus for three theoretical extreme scenarios of biodistribution and pharmacokinetics: 1) all of the injected radiopharmaceutical remains in the breast and is eliminated only by physical decay; 2) all of the injected radiopharmaceutical is instantaneously transported to the urinary bladder, where it remains and is eliminated only by physical decay; and 3) the injected radiopharmaceutical behaves as though it were administered intravenously, that is, it has the biodistribution and pharmacokinetics of Tc-99m sulfur colloid injected for a liver/spleen or bone marrow scan. The fetal radiation absorbed dose was then estimated for two Tc-99m dosages: 18.5 MBq (0.5 mCi) and 92.5 MBq (2.5 mCi). The Medical Internal Radiation Dosimetry (MIRD) program was used to estimate the absorbed doses to the embryo/fetus for the first two scenarios. Published data were used to calculate the doses for the third scenario. A single breast is not among the source organs in the MIRD program, so the heart was used as a surrogate in the first scenario. In the two breast cancer patients, whole-body gamma-camera images obtained 1 hour after radiopharmaceutical injection revealed no radioactivity except in the vicinity of the injection site. In the theoretical scenarios, with 92.5 MBq, the highest absorbed doses to the embryo/fetus were as follows: scenario 1, 7.74 x 10(-2) mGy at 9 months of pregnancy; scenario 2, 4.26 mGy during early pregnancy; and scenario 3, 0.342 mGy at 9 months of pregnancy. The maximum absorbed dose to the fetus of 4.3 mGy calculated for the worst-case scenario is well below the 50 mGy that is believed to be the threshold absorbed dose for adverse effects. Thus breast lymphoscintigraphy during pregnancy appears to present a very low risk to the embryo/fetus.

Publication types

  • Evaluation Study

MeSH terms

  • Breast Neoplasms / diagnostic imaging*
  • Breast Neoplasms / metabolism
  • Female
  • Fetus / metabolism*
  • Humans
  • Lymph Nodes / diagnostic imaging
  • Lymph Nodes / metabolism
  • Lymphatic Metastasis / diagnostic imaging
  • Pregnancy
  • Pregnancy Complications, Neoplastic / diagnostic imaging*
  • Pregnancy Complications, Neoplastic / metabolism
  • Radiation Dosage
  • Radionuclide Imaging
  • Radiopharmaceuticals / pharmacokinetics*
  • Technetium Tc 99m Sulfur Colloid / pharmacokinetics*


  • Radiopharmaceuticals
  • Technetium Tc 99m Sulfur Colloid