‘Watchful waiting’ rather than removal is suitable for most women diagnosed with non-cancerous ovarian cysts, avoiding potential surgical complications, found a two-year study following 1919 women from 10 countries. “Our results may lead to a paradigm shift … on condition that trained ultrasound examiners reliably exclude cancer,” said Professor Tom Bourne, lead researcher from Imperial College London.
This is the finding of research, by a team of international scientists from institutions including Imperial College London and KU Leuven. The two-year study followed 1919 women from 10 different countries, including the UK, Belgium, Sweden and Italy, who were diagnosed with non-cancerous ovarian cysts.
Ovarian cysts are fluid-filled sacs that develop on a woman’s ovary. They’re very common and usually don’t cause any symptoms. However, in some cases they can trigger pelvic pain and bloating. Doctors refer patients with these symptoms for ultrasound scans, where the cysts are classified as benign (non-cancerous), or cancerous tumours. In the event of suspected cancer, the cysts are always removed and analysed.
In the case of cysts that are thought to be benign, women are still often recommended to have the cysts surgically removed. This is because it has been thought that there is a risk of serious complications such as the cyst bursting, or causing the ovaries to twist. There have also been concerns that benign cysts may “turn cancerous” if left in place or that a cyst may have been mis-classified at the initial ultrasound scan.
However, an alternative to surgery is so-called ‘watchful waiting’, where doctors do not remove the cysts, but monitor their size and appearance with regular ultrasound scans. This is because many cysts shrink and disappear or do not change over time.
Opinion is still divided on watchful waiting, with many doctors across the world believing benign cysts should be surgically removed in the majority of cases.
This latest study is the largest to date on the ‘watchful waiting’ approach, which followed nearly 2,000 women as they were scanned in the years after a benign cyst diagnosis. Out of the 1919 women in the trial, one in five (20%) had cysts that disappeared of their own accord, and 16 per cent underwent surgery. Overall, in 80% of case either the cyst resolved or did not need intervention. The average age of the women in the study was 48, and the average size of the cyst was 4cm.
Only 12 women were subsequently diagnosed with ovarian cancer, making the risk of cancer 0.4%. However, the researchers caution this may be due to the tumours being initially misdiagnosed as non-cancerous on the initial ultrasound scan, rather than a benign cyst turning cancerous.
The rate of other complications, such as ovarian twisting or cyst rupture was 0.4% and 0.2% respectively.
The research team say these risks must be assessed alongside the risks of surgical removal. The risk of complications, such as bowel perforation, for surgical removal of cysts among women aged 50-74 is between 3% and 15%.
Professor Dirk Timmerman, lead author from KU Leuven explained: “Despite these surgical risks being small, if the women in this age group underwent surgery in our study then we could speculate that 29 to 123 of them could have suffered severe surgical complications. Instead, only 96 of them underwent surgery, which means severe complications may have been avoided in between 29 to 123 women.”
Professor Tom Bourne, lead researcher from Imperial College London said this study suggests watchful waiting is suitable for most women when an ovarian cyst is initial classified as being benign: “Our results may lead to a paradigm shift resulting in less surgery for non-cancerous ovarian cysts – on condition that trained ultrasound examiners reliably exclude cancer.”
The study was funded by the Research Foundation-Flanders, the Swedish Research Council, The Malmo General Hospital Foundation for fighting against cancer, the National Institute for Health Research (NIHR) Imperial Biomedical Research Centre.
Background: Ovarian tumours are usually surgically removed because of the presumed risk of complications. Few large prospective studies on long-term follow-up of adnexal masses exist. We aimed to estimate the cumulative incidence of cyst complications and malignancy during the first 2 years of follow-up after adnexal masses have been classified as benign by use of ultrasonography.
Methods: In the international, prospective, cohort International Ovarian Tumor Analysis Phase 5 (IOTA5) study, patients aged 18 years or older with at least one adnexal mass who had been selected for surgery or conservative management after ultrasound assessment were recruited consecutively from 36 cancer and non-cancer centres in 14 countries. Follow-up of patients managed conservatively is ongoing at present. In this 2-year interim analysis, we analysed patients who were selected for conservative management of an adnexal mass judged to be benign on ultrasound on the basis of subjective assessment of ultrasound images. Conservative management included ultrasound and clinical follow-up at intervals of 3 months and 6 months, and then every 12 months thereafter. The main outcomes of this 2-year interim analysis were cumulative incidence of spontaneous resolution of the mass, torsion or cyst rupture, or borderline or invasive malignancy confirmed surgically in patients with a newly diagnosed adnexal mass. IOTA5 is registered with ClinicalTrials.gov, number NCT01698632, and the central Ethics Committee and the Belgian Federal Agency for Medicines and Health Products, number S51375/B32220095331, and is ongoing.
Findings: Between Jan 1, 2012, and March 1, 2015, 8519 patients were recruited to IOTA5. 3144 (37%) patients selected for conservative management were eligible for inclusion in our analysis, of whom 221 (7%) had no follow-up data and 336 (11%) were operated on before a planned follow-up scan was done. Of 2587 (82%) patients with follow-up data, 668 (26%) had a mass that was already in follow-up at recruitment, and 1919 (74%) presented with a new mass at recruitment (ie, not already in follow-up in the centre before recruitment). Median follow-up of patients with new masses was 27 months (IQR 14–38). The cumulative incidence of spontaneous resolution within 2 years of follow-up among those with a new mass at recruitment (n=1919) was 20·2% (95% CI 18·4–22·1), and of finding invasive malignancy at surgery was 0·4% (95% CI 0·1–0·6), 0·3% (<0·1–0·5) for a borderline tumour, 0·4% (0·1–0·7) for torsion, and 0·2% (<0·1–0·4) for cyst rupture.
Interpretation: Our results suggest that the risk of malignancy and acute complications is low if adnexal masses with benign ultrasound morphology are managed conservatively, which could be of value when counselling patients, and supports conservative management of adnexal masses classified as benign by use of ultrasound.
Wouter Froyman, Chiara Landolfo, Bavo De Cock, Laure Wynants, Povilas Sladkevicius, Antonia Carla Testa, Caroline Van Holsbeke, Ekaterini Domali, Robert Fruscio, Elisabeth Epstein, Maria José dos Santos Bernardo, Dorella Franchi, Marek Jerzy Kudla, Valentina Chiappa, Juan Luis Alcazar, Francesco Paolo Giuseppe Leone, Francesca Buonomo, Lauri Hochberg, Maria Elisabetta Coccia, Stefano Guerriero, Nandita Deo, Ligita Jokubkiene, Jeroen Kaijser, An Coosemans, Ignace Vergote, Jan Yvan Verbakel, Tom Bourne, Ben Van Calster, Lil Valentin, Dirk Timmerman