Definitions

Inputs
Age	Enter the patient’s age, taking into account any health issues. If the patient is in average health for someone of her age, select the closest age to her actual age. If the patient is in better health than an average woman of her health, it may be an age less than her actual age. If the patient has more health issues that the average woman of her age, this may be greater than her actual age (depending on the severity of her health issues in terms of limiting life expectancy).
10-year invasive recurrence risk	Enter the likelihood of an invasive cancer diagnosis in the next 10 years in the breast affected by DCIS if no further treatment (no radiation or tamoxifen) after excision is performed. The default estimate for this risk is 16% as described by the NSABP B-17 study (Wapnir, 2011).
10-year DCIS recurrence risk	Enter the likelihood of another DCIS diagnosis in the next 10 years in the breast affected by DCIS if no further treatment (no radiation or tamoxifen) after excision is performed. The default estimate for this risk is 14% as described by the NSABP B-17 study (Wapnir, 2011).
Estrogen-receptor status	ER status is not incorporated in the projections, as data from the B17 trial of DCIS was not separated by ER status. However, recent data from the NSABP trial suggests that tamoxifen may only be of benefit in ER-positive patients (REFERENCE, 2012), and therefore the treatment choices containing tamoxifen should not be selected in those patients with ER-negative DCIS.
Diagnosis
DCIS – ductal carcinoma in situ	Pre-invasive or non-invasive carcinoma of the breast. DCIS alone does not spread to the nodes or rest of the body. Once a woman is diagnosed with DCIS she is at increased risk of developing DCIS or invasive breast cancer in both the same and opposite (contralateral) breast.
Margins	The edge of the surgical specimen removed from the breast. If there are cancer cells at the edge of the surgical specimen the margin is said to be “positive.” A “negative” margin is no cancer cells at the edge of the surgical specimen.
Treatments
Radiation therapy	Treatment given daily to the whole breast to reduce the likelihood of having a new diagnosis in the same breast. Once a woman has received radiation therapy to one breast, she cannot receive full course radiation therapy to that breast if a cancer or DCIS is diagnosed in that breast in the future.
Tamoxifen	An oral medication that acts like an anti-estrogen in the breast. When the DCIS expresses the estrogen receptor, tamoxifen can reduce the likelihood that DCIS or invasive cancer is diagnosed in that breast in the future. Tamoxifen also can help prevent cancer for being diagnosed in the other breast.
Mastectomy	Surgical removal of the entire breast.
Reconstruction	Done after mastectomy with either an implant or native tissue (autologous) to recreate the breast contour.
Outcomes
Ipsilateral recurrence	Invasive cancer or DCIS diagnosed in the same breast.
Chest wall recurrence	Invasive cancer or DCIS diagnosed in the same breast because small amounts of breast tissue may remain after the mastectomy.
Mastectomy (with or without reconstruction)	The event that a woman has a mastectomy.
Breast preservation	The event that a woman retains her own breast.
Disease-free life expectancy	The amount of time a patient who has DCIS can expect to be alive without any recurrence of DCIS or diagnosis of a new breast cancer.
Overall life expectancy	The amount of time a patient can expect to live.
Survival	The event of being alive.