Hypofractionated Radiation Therapy vs Standard Treatment in Breast Cancer.

Hypofractionated Radiation Therapy (1 Week) Compared With Standard Treatment (3.1 Weeks), Evaluation of Local Control of Breast Cancer Treated With Conservative Surgery.

An explanatory study comparing complementary treatment to breast conservative surgery with radiation therapy DCIS, T1-T2 N0 M0 (AJCC v8) 1 week schedule vs 3.1 weeks standard schedule, in order to determine the equivalence of local tumor control, survival, acute and chronic toxicity. Shorter curse of radiation therapy may lead to similar local control of tumor cells and lower rates of toxicity than 3.1 standard treatment.

PRIMARY OBJECTIVE:

I. Compare the effectiveness of hypofractionated radiotherapy (1 week) with standard treatment (3.1 weeks) in the local control of breast cancer treated with conservative surgery.

SECONDARY OBJECTIVES:

I. Identify the histological lineage of the tumor.

II. Identify the degree of differentiation of tumor cells.

III. Identify the presence and type of receptors (estrogen, progesterone, HER-2NEU) through immunohistochemistry.

IV. Measure the frequency of progression or recurrence.

V. Identify the site of progression or recurrence.

VI. Measure the frequency of toxicity in both groups.

VII. Classify toxicity according to its severity.

VIII. Classify toxicity according to chronological presentation, acute, subacute, or chronic.

IX. Measure quality of life in both groups according to the European Organization for Research and Treatment Cancer scale, Breast Cancer-Specific Quality of Life Questionnaire, (EORTC, QLQ-BR23).

X. Measure quality of life in both groups according to the Eastern Collaborative Oncology Group (ECOG) performance scale.

XI. Measure 5-year survival.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I: will receive radiotherapy treatment with high hypofractionation, 26 Gy in 5 fractions to the whole breast.

ARM II: will receive radiotherapy treatment with standard hypofractionation, 42.5 Gy in 16 fractions with simultaneous integrated increase of 5.5 Gy to the tumor bed in high-risk patients.

After completion of treatments, patients will be followed: 2 weeks after final fraction, 6 weeks after final fraction, every 4 months for the next 5 years

Inclusion Criteria:

• Patients diagnosed by histopathological report of ductal carcinoma in situ (DCIS) or invasive breast carcinoma.
• Treated with breast-conserving surgery and stage pT1-2 pN0 M0.
• Over 18 years.
• Patients who sign informed consent for research study.

Exclusion Criteria:

• Positive nodes.
• Clinical or pathological stage T3-T4.
• History of previous irradiation.
• Postoperative positive margin.