Ovarian tissue cryopreservation (OTC) is a new approach on fertility preservation for young female patients with cancer. It is now used by many IVF centers in the world. However, this is the first study which OTC by vitrification is carried on and assessed the effectiveness of the technique.

Ovaries from all less than 45 year-old breast cancer patients who undergo oophorectomy by laparoscopy after treated with chemotherapy will be enrolled to the study. Pieces of cortex of each patient will divide into two groups. Group 1 is fresh fragments (control group) and group 2 is vitrified group. Ovarian tissues in group 2 will be vitrified or warmed with medium and devices of Ova-kit type M (Kitazato, Japan).

Cortex fragments of each group will have:

• Follicle survival evaluation by Neutral red staining
• Histological evaluation by Hematoxylin and Eosin staining
• Evaluation relative Growth Differentiation Factor 9 (GDF-9) and Caspase-3 gene expression by real-time Polymerase chain reaction (PCR).

Comparison of data collected from 2 groups will be carried on to evaluate the effectiveness of the technique before applying this technique for cancer patients in Vietnam.

Inclusion Criteria:

• Ovaries from all less than 45 year-old breast cancer patients who undergo oophorectomy by laparoscopy after treated with chemotherapy

Exclusion Criteria:

• The volume of ovaries is less than 2/3 of normal 3cm (L) x 2.5cm (H) x 1.5cm (W) ovary.