Inclusion Criteria:

1. Pathologically proven diagnosis of ductal carcinoma in situ (DCIS) or invasive breast
cancer

2. Ability to have breast conservation as determined by the judgment of the radiation
oncologist

3. The patient must be female

4. Age >= 18

5. Clinical (c)Stage 0 or cStage I

6. If multifocal breast cancer, then it must have been resected through a single
lumpectomy incision with negative margins

7. Appropriate stage for protocol entry, including no clinical evidence for distant
metastases, based upon the following minimum diagnostic workup:

1. History/physical examination, including breast exam and documentation of weight
and Karnofsky performance status of 80-100% for at least 60 days prior to study
entry

2. Ipsilateral mammogram within 6 months prior to study entry

8. Women of childbearing potential must have a negative serum pregnancy test within 14
days of study entry

9. Women of childbearing potential must be non-pregnant and non-lactating and willing to
use medically acceptable form of contraception during radiation therapy

10. Patient must capable of and provide study specific informed consent prior to study
entry

11. Body mass index (BMI) >= 21

12. Weight >= 100 lbs

13. No prior history of non-breast malignancies in the past 5 years unless it was a
non-melanomatous skin lesion or carcinoma in situ of the cervix

14. Patient must not be a candidate to receive chemotherapy

15. Patient must not have any of the following severe, active co-morbidity, defined as
follows:

1. Unstable angina and/or congestive heart failure requiring hospitalization within
the last 6 months

2. Transmural myocardial infarction within the last 6 months

3. Acute bacterial or fungal infection requiring intravenous antibiotics at the
time of registration

4. Chronic obstructive pulmonary disease exacerbation or other respiratory illness
requiring hospitalization or precluding study therapy within 30 days before
registration

5. Hepatic insufficiency resulting in clinical jaundice and/or coagulation defects;
note, however, that laboratory tests for liver function and coagulation
parameters are not required for entry into this protocol

6. Acquired immune deficiency syndrome (AIDS) or human immunodeficiency virus (HIV)
positive based upon current Centers for Disease and Control (CDC) definition;
note, however, that HIV testing is not required for entry into this protocol;
the need to exclude patients with AIDS or HIV from this protocol is necessary
because anti-retrovirals may alter patient metabolism

16. Patient must not have active systemic lupus, erythematosus, or any history of
scleroderma, dermatomyositis with active rash

17. No prior radiotherapy to the ipsilateral breast or prior radiation to the region of
the breast that would result in overlap of radiation therapy fields

18. Patient must have a fasting glucose < 125 mg/mL and not be currently taking
hypoglycemic medications

19. Patient may not have any active gastrointestinal/malabsorption disorder at the
discretion of the Principal Investigator

1. Inflammatory bowel disease

2. Celiac disease

3. Chronic pancreatitis

4. Chronic diarrhea or vomiting

5. Active eating disorder

20. Creatinine < 1.7

21. Not currently taking steroids

22. No currently active pituitary secreting tumors up to physician discretion

23. No history of or current active drug/alcohol dependence

24. No patients being decisionally impaired

Exclusion Criteria:

1. Patient is not a candidate for breast conservation

2. Patient is male

3. Age < 18 years

4. cStage II or above

5. Patient has evidence of distant metastases

6. Karnofsky performance status less than 80% within 60 days prior to study

7. Ipsilateral mammogram done greater than 6 months prior to study

8. Women of childbearing potential with a positive serum beta human chorionic
gonadotropin (hCG)

9. Patient has a history of dementia, psychosis or other disorder affecting their mental
status to the point where they cannot consent or comply with study guidelines

10. BMI < 21

11. Weight < 100 lbs

12. Weight loss >= 10% in the last 3 months (mos)

13. Prior invasive non-breast malignancy (except non-melanomatous skin cancer, carcinoma
in situ of the cervix) unless disease free for a minimum of 5 years prior to
registration

14. Two or more breast cancers not resectable through a single lumpectomy incision

15. Non-epithelial breast malignancies such as sarcoma or lymphoma

16. Prior radiotherapy to the ipsilateral breast or prior radiation to the region of the
breast that would result in overlap of radiation therapy fields

17. Intention to administer concurrent chemotherapy for current breast cancer

18. Severe, active co-morbidity, defined as follows:

1. Unstable angina and/or congestive heart failure requiring hospitalization within
the last 6 months

2. Transmural myocardial infarction within the last 6 months

3. Acute bacterial or fungal infection requiring intravenous antibiotics at the
time of registration

4. Chronic obstructive pulmonary disease exacerbation or other respiratory illness
requiring hospitalization or precluding study therapy within 30 days before
registration

5. Hepatic insufficiency resulting in clinical jaundice and/or coagulation defects;
note, however, that laboratory tests for liver function and coagulation
parameters are not required for entry into this protocol

6. Acquired immune deficiency syndrome (AIDS) or HIV positive based upon current
CDC definition; note, however, that HIV testing is not required for entry into
this protocol; the need to exclude patients with AIDS or HIV from this protocol
is necessary because anti-retrovirals may alter patient metabolism

19. Active systemic lupus, erythematosus, or any history of scleroderma, dermatomyositis
with active rash

20. Fasting glucose > 125 or currently taking hypoglycemic medications

21. Active gastrointestinal/malabsorption disorder at the discretion of the Principal
Investigator

1. Inflammatory bowel disease

2. Celiac disease

3. Chronic pancreatitis

4. Chronic diarrhea or vomiting

5. Active eating disorder

22. Creatinine >= 1.7

23. Current use of steroids

24. Pituitary secreting tumors up to physician discretion

25. Active drug/alcohol dependence or abuse history

26. Decisionally impaired patients