A new study led by Dr. Rachel Grisham and Dr. Beryl Manning-Geist (pictured) from Memorial Sloan Kettering Cancer Center has found that while response rates to chemotherapy are lower than high-grade serous subtypes, this treatment remains an important tool for patients.
LGSOC is known to be relatively resistant to chemotherapy, especially before surgery (neo-adjuvant) and when the cancer returns. This retrospective study looked at how well patients with LGSOC responded to chemotherapy both during initial treatment and after recurrence. It included 50 patients treated at Memorial Sloan Kettering between 1998 and 2021.
Key Findings
Treatment of Newly Diagnosed LGSOC
- Among 12 patients who had platinum-based chemotherapy after surgery (when surgery couldn’t remove all visible cancer), 58% saw their tumors shrink. This is significantly higher than in a previously reported study of 39 patients where only 23% showed a response.
- For the 11 patients who received platinum-based chemotherapy before surgery (neo-adjuvant chemotherapy), only 9% experienced tumor shrinkage, which is consistent with other studies reporting rates of 4-11%. Despite this, 50% of these patients still had all visible cancer removed during surgery, and 40% had their cancer reduced to 1 cm or less.
Implications for Neo-Adjuvant Treatment Selection
Neo-adjuvant chemotherapy is usually given when cancer is too advanced for immediate surgery, to shrink the tumor and make surgery easier. However, this study showed that 90% of patients who had neo-adjuvant chemotherapy were still able to have most of their cancer removed through surgery, even though the chemotherapy wasn’t very effective in shrinking tumours.
This raises the question of whether doctors should be more selective in choosing who receives neo-adjuvant treatment because response rates were better when surgery was performed first. It also emphasizes the importance of identifying newer, more effective treatments for patients who require neoadjuvant chemotherapy before an attempted debulking surgery.
Treatment of Recurrent LGSOC
- Among the 44 patients whose cancer returned, the response to platinum-based chemotherapy was modest. 22% of patients responded to a platinum-based regimen during their second round of treatment, and this dropped to 10% during their third round. This is better than some other studies that reported response rates of 2-5%.
- Non-platinum chemotherapy combined with bevacizumab showed better results though numbers were small. In the second round of treatment, two out of two patients who received this combination responded positively.
Implications for Recurrent Disease
Typically, “platinum sensitivity” means cancer doesn’t return within six months of platinum-based chemotherapy. This definition works well for high-grade ovarian cancer, but may not apply as well to LGSOC. Even when patients in this study were considered platinum-sensitive, their response to platinum-based chemotherapy was still low. This suggests that non-platinum chemotherapy, especially when combined with bevacizumab, may be more effective for some patients.
Limitations
While this study offers valuable insights, there are some limitations to keep in mind:
- The sample size was small, so the results may not apply to all patients with LGSOC.
- As a retrospective study, it looked at past cases, which can lead to variability in how results are measured and interpreted.
- The study focused on tumor shrinkage, but it’s important to note that even if tumors don’t shrink, chemotherapy can still sometimes stop cancer from growing, or keep disease “stable.”
Larger studies are needed to confirm these findings before they can be used in routine clinical practice.
Conclusion
This study found higher rates of tumor shrinkage with chemotherapy in newly diagnosed patients who had surgery before chemotherapy. However, due to the small sample size, further research is needed. For patients receiving neo-adjuvant chemotherapy or being treated after cancer returns, the response rates were lower, highlighting the challenges in treating LGSOC and the need for better treatment options.
Definitions
- Response rate refers to the proportion of people who experience tumour shrinkage with treatment.
- Examples of platinum chemotherapy include carboplatin and cisplatin.
- Examples of non-platinum chemotherapy include paclitaxel and pegylated liposomal doxorubicin (PLD).
Acknowledgements
Review by study co-lead Dr Beryl Manning-Geist
Study Full Text
Original study published March 2023
