To compare the Overall survival of adjuvant chemotherapy versus observation in stage I epithelial ovarian cancer after comprehensive staging surgery

Based on the following adjustment factors, patients will be randomly assigned in a 1:1 ratio to adjuvant chemotherapy or observation groups.

1. Histologic type: clear cell adenocarcinoma/mucinous adenocarcinoma vs. serous adenocarcinoma/other histologic types
2. Facility where a subject is enrolled
3. International Federation of Gynecology and Obstetrics(FIGO) clinical staging: Stage Ia/ Ib vs. Stage Ic(b)

Group A: adjuvant chemotherapy group (standard treatment group):

While one of the following treatments will be performed, the number of cycles is entrusted to the treatment policy of each facility.

Paclitaxel plus Carboplatin (TC) therapy; Paclitaxel (PTX) 175 mg/m2 + Carboplatin(CBDCA) area under curve(AUC) 6 q3weeks day1, 3 to 6 cycles Docetaxel plus Carboplatin (DC) therapy; Docetaxel(DTX) 70 mg/m2 + CBDCA AUC 6 q3weeks day1, 3 to 6 cycles

After the start of TC therapy, switching from PTX to DTX due to an adverse event is permitted.

Group B: observation group (study treatment group): Observation only, no adjuvant chemotherapy administered.

Inclusion Criteria:

1. Patients with a diagnosis of histopathologically epithelial ovarian cancer

2. FIGO Stages Ia(Grade2/3, clear cell carcinoma), Ib(Grade2/3, clear cell carcinoma) and Ic(b)(all degree of differentiation and all histologic type)

3. Patients with a diagnosis of advanced stage by comprehensive staging or restaging laparotomy.

4. Patients who received comprehensive staging surgery (basic surgical techniques (total hysterectomy, bilateral salpingo-oophorectomy, and omentectomy) as well as peritoneal cytology, multiple biopsies of the peritoneum ([Peritoneal biopsy] see details below), retroperitoneal lymph node dissection (see details below [Retroperitoneal lymph node dissection]).

   However, for the following cases, it is eligible as a condition to record on the official document.

   • Peritoneal biopsy: peritoneal metastasis is not recognized by macroscopic and palpation in the stipulated site, and the case that biopsy has not been performed.
   • Retroperitoneal lymph node dissection: the case that lymph nodes of the stipulated range has been dissected however the prescribed number has not been reached.

5. Age: 20 or older

6. Performance status (PS):0-1

7. Case with initial therapy for postoperative primary lesion

8. Patient possible to receive the first study treatment within 8 weeks after the comprehensive staging surgery

9. Reasonable organ function

10. Patient must have signed informed consent.

Exclusion Criteria:

1. FIGO Stages Ic(a), Ic(1) and Ic(2)
2. Patients containing sarcoma elements
3. Patients with any signs of interstitial pneumonia or pulmonary fibrosis by chest radiography and CT
4. Patients with serious complications
5. Patients with active infection
6. Patients with intestinal paralysis or intestinal obstruction
7. Patients who have a synchronous malignancy or who have been progression-free less than 5 years for a metachronous malignancy
8. Patients with previous chemotherapy or radiation therapy
9. Patients with serious drug hypersensitivity
10. Patients with peripheral motor/sensory neuropathy [grade2,3,4 Common Terminology Criteria for Adverse Events (CTCAE) 4.0]
11. Patients who have had a hypersensitivity reaction to polyoxyethylated or hydrogenated castor oil
12. Patients with positive HBsAg. Patients with more than 2.1 log/copies ml based on fixed Hepatitis B virus (HBV)-DNA who are positive with either antigen-positive Hepatitis B (HBs), anti-hepatitis B core antigen or anti-hepatitis B surface antigen.
13. Patients who are inappropriate to enter this study with any safety reasons, judged by the treating physician