This is a pain survey study that will compare the level of discomfort experienced by breast cancer patients after injection of either technetium-labeled sulfur colloid or technetium-labeled tilmanocept, both FDA-approved agents used for sentinel lymph node biopsy (SLNB). Breast cancer patients who are already scheduled for SLNB as part of their original surgical plan will be asked to participate in this study and be randomized to receive either technetium-labeled sulfur colloid or technetium-labeled tilmanocept. After injection, patients will complete pain questionnaires to measure the amount of discomfort they are feeling during and after they receive the injection. There will be no change to the patient's treatment plan other than the addition of pain questionnaires. The investigators' hypothesis is that patients will feel less discomfort after injection of tilmanocept versus sulfur colloid.

Inclusion Criteria:

• The patient has a diagnosis of biopsy-proven primary breast cancer or a diagnosis of pure ductal carcinoma in situ (DCIS) who will be undergoing intraoperative lymphatic mapping as part of their standard surgical plan.
• The patient has provided written informed consent before participating in the study, as has his/her responsible caregiver, if applicable.
• The patient is a candidate for surgical intervention, with lymph node mapping being a part of the surgical plan.
• The patient is greater than 18 years of age at the time of consent.
• The patient has an performance status of Grade 0 - 2.
• The patient has a clinical negative node status at the time of study entry.
• If the patients is of child bearing potential, the patient has a negative pregnancy test within 72 hours prior to administration of radiopharmaceutical, has been surgically sterilized, or has been postmenopausal for at least 1 year.

Exclusion Criteria:

• The patient is pregnant or lactating.
• The patient has clinical or radiological evidence of metastatic cancer including palpably abnormal or enlarged lymph nodes

Female patients, aged 18 years or older with a diagnosis of primary breast cancer or ductal carcinoma in situ (DCIS) with planned Sentinel node biopsy (SLN) biopsy as part of the surgical plan were approached at preoperative clinic visits of the principal investigator. (Anne Wallace)