Ovarian Cancer: New Measure of Benefit Proposed
Veronica Hackethal, MD
January 07, 2015
For patients with ovarian cancer who are in remission, the probability of remaining disease-free improves considerably over time, and conditional disease-free survival might be a good estimate of prognosis for these patients, according to a new study.
The study, which was published in the December issue of Journal of Clinical Oncology, is the first to look at conditional disease-free survival in patients with ovarian cancer.
“We observed that at time of remission, the probability of staying disease-free for 3 more years was 48%. This increased to 98% for patients who had remained disease-free for 5 years after remission,” said lead author Brenda Diergaarde, PhD, assistant professor of epidemiology at the University of Pittsburgh Cancer Institute.
Prognosis usually improves over time, Dr Diergaarde pointed out. Traditional survival estimates, like overall survival (estimated at diagnosis) and disease-free survival (estimated at remission), might not apply to patients in remission for a certain period of time.
Conditional disease-free survival, however, takes into account changes in the probability of remaining disease-free over time, as well as the amount of time since achieving remission, Dr Diergaarde explained.
“Time elapsed since remission should be taken into account when making follow-up care decisions,” Dr Diergaarde emphasized. “Having more accurate information about the risk of recurrence will allow patients and clinicians to make better informed decisions regarding follow-up care after ovarian cancer treatment. It may also lead to a better quality of life [for patients] because a more accurate prognosis can ease their fears about the cancer coming back.”
Estimation of Conditional Disease-free Survival
In their study, Dr Diergaarde and colleagues used data from 404 patients with ovarian, fallopian, and peritoneum cancer who were diagnosed from 2003 to 2008 and who had achieved remission. All patients were part of the large case–control Hormones and Ovarian Cancer Prediction (HOPE) study.
The HOPE study involves patients from western Pennsylvania, eastern Ohio, and western New York who entered the study within 9 months of their diagnosis. Researchers gathered demographic and lifestyle information at study enrollment, and used medical records to obtain information on disease, treatment, and outcomes. They calculated disease-free survival as the amount of time between remission and recurrence, or date of last contact, and estimated conditional disease-free survival from cumulative disease-free survival estimates.
Most patients (96.8%) were white, and 5.5% had a family history of ovarian or breast cancer. Patients who had already survived 1, 2, 3, 4, or 5 years had a probability of 3 more years of recurrence-free survival of 63.8%, 80.5%, 90.4%, 97.0%, and 97.7%, respectively.
The probability of being disease-free 5 years after achieving remission increased from 44.6% at baseline to 63.3%, 80.5%, 92.4%, and 99.2%, respectively, 1, 2, 3, and 4 years into remission.
Although conditional disease-free survival always increases as the number of years spent in remission increases, certain subgroups in this study experienced larger increases, Alexia Lasonos, PhD, a biostatistician at the Memorial Sloan Kettering Cancer Center in New York City, pointed out in an accompanying podcast.
“The increase was larger for patients above 65 years of age, patients with advanced-stage disease, serous histology, and poorly differentiated tumors,” Dr Lasonos said. “This indicates that conditional disease-free survival improves most for patients who initially had the poorest prognosis.”
At the time of remission, disease-free survival estimates also varied, depending on age, stage, histology, and grade. These factors were important for patients who remained in remission for 3 years, she explained.
“If a patient was still in remission 4 years later, her age, stage, histology, and grade at diagnosis were no longer diagnostic in terms of disease-free survival,” she added. “What mattered most at that time is the fact that the patient had been in remission for 4 years.”
Dr Lasonos urged caution, though, when interpreting the results of this study. Conditional disease-free survival estimates always have a larger degree of uncertainty than baseline estimates, she noted. This is because fewer patients remain in remission over time.
In addition, results suggest that risk for recurrence is significantly higher in patients on maintenance chemotherapy. However, high-risk patients are more likely to have received maintenance chemotherapy, which could have biased these results. Other limitations of the study could have been its observational nature and its lack of a standardized surveillance group.
Nevertheless, Dr Lasonos commended Dr Diergaarde’s team for their work.
“With new successful treatments and advances in immunotherapy that have extended time in remission for this patient population, these conditional estimates become more relevant for ovarian cancer patients,” Dr Lasonos emphasized.
Future research will need to focus on developing prognostic tools that take time in remission into account, she concluded.
“This is an important contribution to both the literature and the discussion of the way survival outcomes might optimally be presented to cancer patients,” said Maurie Markman, MD, senior vice president for clinical affairs at the Cancer Treatment Centers of America in Philadelphia, and Medscape video blogger for Markman on Oncology, who was not involved in the study.
“Until this report, we really did not have a solid strategy to develop specific numbers that could be provided to patients who have already survived a period of time without recurrence,” Dr Markman explained. “Hopefully, in the future, the concept of conditional disease-free survival will become a regular part of discussions within the oncology community and with patients,” he said.
Dr Diergaarde and Dr Lasonos have disclosed no relevant financial relationships. Dr Markman reports receiving fees from Celgene, Caris Life Sciences, Novartis, sanofi-aventis, Amgen, and Genentech.
Article courtesy www.medscape.com/