Inclusion Criteria:

- Participants must have a diagnosis of estrogen receptor positive (more than 5% cells
staining for ER), grade 2 or 3 (using definition of Page and Lagios) ductal carcinoma
in situ (DCIS) with no evidence of invasion on diagnostic core needle biopsy within
the previous 60 days

- ECOG performance status =< 1(Karnofsky >= 70%)

- Leukocytes >= 3,000/uL

- Absolute neutrophil count (ANC) >= 1,500/uL

- Platelets >= 100,000/uL

- Total bilirubin within normal institutional limits

- AST (SGOT)/ALT (SGPT) =< 1.5 X institutional ULN

- Creatinine within normal institutional limits

- Women of child-bearing potential must agree to practice barrier birth control,
abstinence, or use non-hormonal IUDs from the time that the first pregnancy test is
performed throughout the duration of the study and for three months after cessation
of study drug; should a woman become pregnant or suspect she is pregnant while
participating in this study, she should inform her study physician immediately

- Ability to understand and the willingness to sign a written informed consent document

- Ability and willingness to schedule surgical resection of DCIS lesion for 6-10 weeks
(42-70 days) following the start of study agent

- Willingness to avoid exposing breast skin to natural or artificial sunlight (i.e.
tanning beds) for the 6-10 weeks of study agent dosing

Exclusion Criteria:

- Participants must not have palpable DCIS

- Participants should not have a mass lesion >= 5mm on mammogram or ultrasound, or an
area of calcifications greater than 5cm on mammogram

- Participants with DCIS of comedo subtype (i.e. solid DCIS, nuclear grade 3, and
confluent necrosis) will be excluded

- Participants with a prior history of, or at high risk to develop, thromboembolic
disease will be excluded

- Participants must not have taken exogenous sex hormones since biopsy diagnosing DCIS
and must agree not to use exogenous sex hormones while on study

- Participants must not have taken tamoxifen or other selective estrogen receptor
modulators (SERMs) within 2 years prior to entering the study; women who have
discontinued SERM therapy because of thromboembolic or uterine toxicity, will be
excluded regardless of duration of use

- Participants may not be receiving any other investigational agents

- History of allergic reactions attributed to compounds of similar chemical or biologic
composition to 4-hydroxytamoxifen or tamoxifen

- Uncontrolled intercurrent illness including, but not limited to, ongoing or active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance with
study requirements

- Pregnant women are excluded from this study; women are excluded from enrolling within
3 months of the most recent pregnancy; women must avoid becoming pregnant in the 3
months following the use of study agent

- Women must not have breastfed within three months prior to DCNB; women must agree to
forego breastfeeding for three months following the use of study agent

- Participants must not have any dermatologic conditions resulting in skin breakdown in
the area of gel application

- Participants must not have a history of previous invasive or non-invasive breast
cancer

- Participants must not have had a breast reduction or augmentation within the 6 months
prior to first dose of study agents; patients who have had breast implants more than
6 months prior to first dose of study agents will be eligible