# Low-grade serous ovarian cancer

Source: https://onco.cc/cancers/low-grade-serous-ovarian-cancer/  
OnCo record `low-grade-serous-ovarian-cancer` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Low-grade serous cancer is the slow-growing, chemotherapy-resistant cousin of the common ovarian cancer. Surgery and hormone therapy are its mainstays, and MEK inhibitors, alone or combined with a FAK inhibitor, are the first drugs shown to shrink it reliably.

## Summary

Low-grade serous carcinoma is a distinct disease with wild-type TP53 and mutations in the MAPK pathway (KRAS, BRAF, NRAS) in about half of cases; it often arises from a serous borderline tumour and expresses oestrogen receptors. Complete surgical removal matters more than in high-grade disease because chemotherapy response rates are low; letrozole or other aromatase inhibitors are used as maintenance and for recurrence. The GOG 281 trial showed that the MEK inhibitor trametinib nearly doubled progression-free survival compared with standard chemotherapy or hormone therapy in recurrent disease, and the combination of avutometinib and defactinib was approved in the United States in 2025 for KRAS-mutant recurrent disease after the RAMP 201 trial.

## Fields

- Kind: Cancer
- Last checked: 2026-09-17
- Also known as: LGSOC; Low-grade serous carcinoma
- Tags: subtype-page
- Group: gynaecological
- Burden: About one in twenty ovarian cancers, affecting younger women, with a median age in the forties; it grows slowly but resists chemotherapy, so patients live for years with disease that is hard to eradicate.
- Subtypes: KRAS-mutant (most responsive to MEK and RAF/MEK inhibition); BRAF or NRAS-mutant; MAPK wild-type; Arising from serous borderline tumour
- Biomarkers: KRAS, BRAF and NRAS mutations; Oestrogen and progesterone receptor expression; Wild-type TP53 (distinguishes it from high-grade); CA-125 (less reliable than in high-grade disease)

## Standard of care

- First line: Complete cytoreductive surgery; carboplatin-paclitaxel followed by letrozole maintenance, or letrozole alone in selected patients. ([Carboplatin](https://onco.cc/drugs/carboplatin/), [Paclitaxel / nab-paclitaxel](https://onco.cc/drugs/paclitaxel/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/))
- Recurrent disease: Trametinib (GOG 281) or avutometinib plus defactinib for KRAS-mutant tumours; aromatase inhibitors; secondary surgery where complete resection is possible. ([Trametinib](https://onco.cc/drugs/trametinib/), [Avutometinib + defactinib](https://onco.cc/drugs/avutometinib-defactinib/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/))
- Maintenance: Letrozole after first-line treatment, continued for years while tolerated. ([Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/))

## State of the art

- GOG 281 was the first randomised trial in this rare disease and made trametinib a standard option.
- Avutometinib-defactinib is the first approval specific to low-grade serous cancer.
- Hormone maintenance is replacing chemotherapy in first-line care.

## Open problems

- Whether first-line chemotherapy adds anything to surgery and hormone therapy.
- Options for MAPK wild-type tumours.
- Living for decades with a slow but incurable disease.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Ovarian_cancer
- Wikipedia: https://en.wikipedia.org/wiki/Ovarian_cancer

## Connected records

- drugs: [Avutometinib + defactinib](https://onco.cc/drugs/avutometinib-defactinib/), [Carboplatin](https://onco.cc/drugs/carboplatin/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Paclitaxel / nab-paclitaxel](https://onco.cc/drugs/paclitaxel/), [Trametinib](https://onco.cc/drugs/trametinib/)
- cancers: [Ovarian cancer](https://onco.cc/cancers/ovarian/)

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JSON: https://onco.cc/api/v1/entities/low-grade-serous-ovarian-cancer.json