Borderline Ovarian Tumors: How They Differ From Ovarian Cancer

Borderline ovarian tumors are a distinct group of ovarian growths that behave differently from typical ovarian cancer. They are often less aggressive, but they still need expert diagnosis, careful treatment planning, and follow-up.

Overview: What Are Borderline Ovarian Tumors?

Borderline ovarian tumors are ovarian tumors with what doctors often call low malignant potential. This means that under the microscope, the cells look abnormal and show some features linked with cancer, but they do not invade tissue in the same way as typical invasive ovarian cancer. Because of this, they are considered a separate category rather than simply an early form of ovarian cancer.

These tumors most often arise from the surface layer of the ovary, known as the epithelium. The most common subtypes are serous and mucinous borderline tumors. They can occur at different ages, including in younger women, and are sometimes found during imaging, surgery, or evaluation for pelvic symptoms.

A key difference is behavior. Borderline ovarian tumors tend to grow more slowly and are less likely to spread aggressively than invasive ovarian cancers. Many are diagnosed at an earlier stage, and outcomes are often favorable with proper treatment. Still, they should not be dismissed as harmless, because some can recur and a small number may behave more aggressively.

For patients, the term can be confusing because it includes the word “tumor” but not always “cancer.” In practice, management usually involves specialists in gynecology, pathology, imaging, and sometimes oncology to confirm the diagnosis and choose the safest approach.

How They Differ From Ovarian Cancer

The main difference between borderline ovarian tumors and invasive ovarian cancer is how the cells behave. In invasive ovarian cancer, abnormal cells grow into the supporting tissue of the ovary and can spread more destructively within the pelvis or abdomen. In borderline tumors, the cells are atypical, but there is no destructive stromal invasion, which is a central pathologic feature doctors use to distinguish them.

This difference affects treatment and prognosis. While invasive ovarian cancer often requires extensive surgery and may also need chemotherapy, borderline ovarian tumors are usually managed primarily with surgery. Chemotherapy is not routinely used in the same way because these tumors generally do not respond or behave like typical invasive cancers.

Another important distinction is outlook. Many patients with borderline ovarian tumors have excellent long-term survival, especially when the tumor is confined to the ovary. However, follow-up still matters because recurrence can occur, particularly if conservative surgery is chosen to preserve fertility or if disease exists beyond the ovary.

Even though these tumors are often less aggressive, only careful pathology can confirm the diagnosis. Imaging tests and symptoms alone cannot reliably tell the difference between a benign ovarian cyst, a borderline tumor, and invasive ovarian cancer.

Symptoms and Possible Signs

Borderline ovarian tumors may cause no symptoms at all, especially when they are small. In some cases, they are found incidentally during a pelvic exam, ultrasound, or surgery for another reason. When symptoms do occur, they can be similar to those caused by many other ovarian or pelvic conditions.

Possible symptoms may include:

• Pelvic or lower abdominal pain
• Bloating or a feeling of abdominal fullness
• A noticeable increase in abdominal size
• Pressure on the bladder or bowel
• Changes in urination or bowel habits
• Menstrual irregularities in some patients
• Pain during intercourse

These symptoms are not specific to borderline ovarian tumors. They can also occur with benign ovarian cysts, endometriosis, uterine fibroids, or invasive ovarian tumors. That is why ongoing, unexplained pelvic symptoms should be assessed rather than self-diagnosed.

Large tumors are more likely to cause pressure symptoms. Rarely, an ovarian mass can twist on itself, a condition called torsion, which can cause sudden severe pain and requires urgent medical attention.

Causes and Risk Factors

The exact cause of borderline ovarian tumors is not fully understood. Like many ovarian tumors, they likely develop through a combination of cellular changes, hormonal influences, and individual risk factors. In most patients, there is no single identifiable cause.

Some risk factors may overlap with those linked to epithelial ovarian tumors in general. These can include increasing age, a personal or family history of ovarian tumors, and certain reproductive factors. However, borderline ovarian tumors can also affect younger women more often than typical invasive ovarian cancer, so age alone does not provide a clear answer.

Doctors also consider whether a pelvic mass could be related to other gynecologic conditions. Some ovarian growths may resemble ovarian cysts on imaging, especially before surgery and pathology provide a final diagnosis. This is one reason why evaluation by experienced specialists is helpful.

Having a risk factor does not mean a person will develop a borderline ovarian tumor, and having no known risk factors does not rule it out. At present, there is no proven way to predict most cases with certainty.

How Diagnosis Is Made

Diagnosis usually begins with a medical history, symptom review, and pelvic examination. If an ovarian mass is suspected, the next step commonly includes imaging, especially pelvic ultrasound. Ultrasound can show the size, shape, and internal features of an ovarian mass, but it cannot definitively determine whether the mass is benign, borderline, or invasive.

Additional imaging such as MRI or CT may be recommended in selected cases, particularly if the mass is complex, large, or associated with possible spread beyond the ovary. Blood tests, including tumor markers such as CA-125, may also be used, but these markers are not specific. A normal result does not exclude a borderline tumor, and an elevated result does not prove invasive cancer.

The definitive diagnosis is made by pathology. This usually means examining tissue after surgery or, in some settings, during the operation with a rapid preliminary assessment. The pathologist looks for the cellular patterns that define a borderline tumor and, most importantly, checks whether there is stromal invasion that would suggest invasive cancer instead.

Accurate diagnosis is important because treatment planning depends on it. The surgical approach, the extent of tissue removal, and decisions about fertility preservation are all guided by the final pathology findings and the stage of disease.

Treatment Options and Fertility Considerations

Surgery is the main treatment for borderline ovarian tumors. The exact operation depends on factors such as the patient’s age, symptoms, desire for future pregnancy, tumor size, whether one or both ovaries are involved, and whether the disease appears limited to the ovary or extends farther. In many cases, surgery both confirms the diagnosis and removes the tumor.

For patients who wish to preserve fertility and have disease that seems confined, fertility-sparing surgery may be possible. This may involve removing only the affected ovary or removing the tumor while preserving the uterus and some ovarian tissue when medically appropriate. For others, more extensive gynecologic oncology surgery may be advised to reduce the chance of recurrence and to stage the disease properly.

Unlike typical invasive ovarian cancer, chemotherapy is not routinely the standard treatment for most borderline ovarian tumors. Because these tumors behave differently, treatment often focuses on complete surgical management and follow-up rather than systemic therapy. However, each case is individual, especially if implants or more complex findings are present.

Pathology details also matter. Some borderline tumors have features associated with a higher risk of recurrence, so the care plan may differ from one patient to another. Near the end of the treatment journey, some patients may seek care in centers with multidisciplinary expertise; Acibadem International’s specialists in women’s health, oncology, surgery, and imaging at JCI-accredited hospitals diagnose and treat ovarian tumors for international patients.

Follow-Up, Self-Care, and When to See a Doctor

After treatment, regular follow-up is important. This may include pelvic exams, imaging, and symptom review over time. Follow-up schedules vary depending on the type of surgery, the tumor subtype, stage, and whether fertility-sparing treatment was performed. Even though the outlook is often very good, recurrence is possible, and it may happen years later.

Self-care after surgery includes following medical instructions, allowing time for recovery, and attending all scheduled appointments. Patients should report new or persistent symptoms such as bloating, pelvic pain, increasing abdominal size, or changes in urinary or bowel habits. These symptoms do not always mean recurrence, but they deserve evaluation.

A doctor should be consulted promptly for ongoing pelvic symptoms, a newly found pelvic mass, or any symptoms that interfere with daily life. Urgent medical care is needed for sudden severe abdominal or pelvic pain, fainting, or signs of an acute complication.

Because borderline ovarian tumors can resemble other conditions and because treatment choices may affect fertility and long-term health, specialist assessment is valuable. A gynecologist or gynecologic oncologist can help explain the diagnosis clearly and tailor care to the individual patient’s goals.

Frequently asked questions

Are borderline ovarian tumors cancer?

Borderline ovarian tumors are not the same as invasive ovarian cancer. They have abnormal cells and need treatment, but they usually do not invade tissue in the destructive way typical ovarian cancers do.

Can borderline ovarian tumors spread?

They can sometimes involve areas outside the ovary, but they usually behave less aggressively than invasive ovarian cancer. The exact risk depends on the tumor subtype, stage, and pathology findings.

Is surgery always needed?

Surgery is usually the main part of diagnosis and treatment because tissue examination is needed to confirm the condition. The extent of surgery varies and may be more conservative in selected patients, especially when fertility preservation is important.

Can a woman still have children after treatment?

In some cases, yes. If the tumor is limited and the patient wants future pregnancy, fertility-sparing surgery may be possible, but the decision depends on the individual case and should be discussed with a specialist.

Do borderline ovarian tumors come back?

They can recur, especially after conservative surgery, which is why long-term follow-up is important. Many recurrences are still treatable, but monitoring should not be skipped.

Can imaging tests tell the difference between a borderline tumor and ovarian cancer?

Imaging can show whether an ovarian mass looks simple or complex, but it usually cannot provide a definite diagnosis on its own. Final confirmation typically requires pathology after surgical removal or sampling.

References

• World Health Organization
• American Cancer Society
• National Cancer Institute
• American College of Obstetricians and Gynecologists
• National Comprehensive Cancer Network

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.