Clear Cell Ovarian Cancer

Around 13% of all epithelial ovarian cancers are sub-type called clear cell carcinomas (OCCC). OCCC was formally described by the World Health Classification in 1973 as “tumours composed of clear cells containing glycogen and resembling those of the renal cell carcinoma and/or with the presence of hobnail cells”. They are traditionally considered high-grade carcinomas.

Women and people with a clear cell diagnosis are often younger, the average age at diagnosis being 55, compared to 64 in serous carcinoma. This type of ovarian cancer is more much common in Japan, with a prevalence of 25%, the reasons for this aren’t currently known. 

What are the risk factors? 

Endometriosis has been associated with 33%-37% of clear cell ovarian cancers. Unlike high-grade serous ovarian cancers or endometrioid cancers, there is no link with family history and clear cell cancers.  

I have endometriosis, will I get cancer? 

For the majority of women and people with endometriosis doesn’t lead to a cancer diagnosis. 

How is clear cell cancer treated? 

The standard care for clear cell ovarian cancer involves debulking surgery followed by six cycles of 2 weekly post-operative chemotherapy of carboplatin and paclitaxel, which is the same as with other epithelial ovarian cancers.

Clear cell cancers tend to respond less well to chemotherapy than other ovarian cancers- with chemotherapy response rates in recurrent disease ranging between 1-9%. This highlights the need for more research into other treatment strategies, and new, more targeted treatments. 

What about genetics and clear cell? 

Genetically, 85% of clear cell ovarian cancers have wild-type TP53 and a lower frequency of BRCA1 and BRCA2 germline alterations compared to high grade serous ovarian cancers (HGSOC). This means that newly approved drugs such as PARP inhibitors, which are used in BRCA1/2 alteration positive cancers, may be limited. The most frequent alterations associated with clear cell are the on the ARID1A gene, which may give some opportunities for new treatments in the future. 

If you have any questions please do contact our Ask Eve Specialist Information Nurse, Hilary Maxwell either by email or by phone 0808 802 0019.