Ovarian Low Malignant Potential Tumour

Ovarian low malignant potential tumours are abnormal growths that develop in the ovaries. Unlike typical cancers, these tumours have unusual cells that may become cancer but usually do not, and they often affect younger women with an excellent chance of recovery.

borderline ovarian tumor, low malignant potential tumor, borderline tumor

• Ovaries
• Fallopian tubes
• Uterus

Table of contents

• What is an ovarian low malignant potential tumour?
• Types of borderline ovarian tumours
• Who is affected?
• Signs and symptoms
• Diagnosis
• Outlook and survival
• Treatment options
• Follow-up care

What is an ovarian low malignant potential tumour?

An ovarian low malignant potential tumour is a disease in which abnormal cells form in the tissue covering the ovary^[1]. These tumours have abnormal cells that may become cancer, but usually do not^[1]. The disease usually remains in the ovary, and when found in one ovary, the other ovary should also be checked carefully for signs of disease^[1].

The ovaries are a pair of organs in the female reproductive system. They are located in the pelvis, one on each side of the uterus (the hollow, pear-shaped organ where a fetus grows). Each ovary is about the size and shape of an almond. The ovaries make eggs and female hormones^[1].

Ovarian low malignant potential tumours start in the tissue that covers the outside of the ovary^[2]. They usually grow slowly and stay inside the ovary^[2]. These tumours are usually not cancerous, but they should be monitored closely as they can become malignant^[3].

Types of borderline ovarian tumours

There are several types of borderline ovarian tumours, each with different characteristics^[5]:

• Serous tumours are the most common type. They start in the surface of the ovary and often affect younger women. They are filled with fluid and often found in both ovaries^[5].
• Mucinous tumours are the second most common type. They are filled with mucus-like fluid and usually affect only one ovary^[5].
• Endometrioid tumours are rare. They have cells similar to those lining the uterus (called the endometrium) and are often linked to endometriosis^[5].
• Clear cell tumours are very rare and made of clear cells^[5].
• Seromucinous tumours are another very rare type that share features with both serous and mucinous tumours^[5].
• Borderline Brenner tumours are extremely rare tumours that form in the tissue covering the ovary^[5].

The less common endometrioid tumour of low malignant potential should not be regarded as malignant because it seldom, if ever, spreads to other parts of the body. However, malignant transformation can occur and may be associated with a similar tumour outside of the ovary^[8].

Who is affected?

Borderline ovarian tumours make up nearly 20% of ovarian epithelial cancers (cancers that begin in the cells covering the ovary) and have an excellent prognosis regardless of stage at diagnosis^[7]. These tumours are typically diagnosed in patients during their 40s, significantly earlier than invasive carcinomas^[7].

Doctors don’t know exactly why some women get these tumours. They seem to be more common in women who used fertility drugs for more than 1 year without getting pregnant. Women who never get pregnant may also have a higher risk^[2]. These tumours most often affect younger women and can affect their ability to have children^[2].

A family history of ovarian cancer may increase the risk. Other factors that have been linked to this disease include smoking, oral contraceptive use, age at first menstruation, age at first pregnancy and delivery, and age at menopause^[3]. However, these tumours have not been shown to have a hereditary component^[7].

Signs and symptoms

It is possible to have an ovarian low malignant potential tumour and not know it right away. In its early stages, the tumour may not cause early signs or symptoms^[1]. However, as it continues to grow, you may experience certain signs^[3].

If you do have signs or symptoms, they may include^[1]:

• Pain or swelling in the abdomen (belly area)
• Pain in the pelvis
• Gastrointestinal problems, such as gas, bloating, or constipation

Other symptoms that may appear include^[5]:

• Swelling in the stomach area or abdomen
• Vaginal bleeding unrelated to menstrual cycle
• Pain during or after intercourse
• Feeling full soon after eating
• More frequent bowel movements
• Needing to urinate more frequently

You could have those symptoms for many other reasons. Most of the time, it’s not an ovarian tumour^[2]. These signs and symptoms may be confused with other gastrointestinal issues^[3]. However, if they get worse or do not go away on their own, you need to see a doctor to find out^[1].

Diagnosis

Tests that examine the ovaries are used to diagnose and stage ovarian borderline tumour. In addition to asking about your personal and family health history and doing a physical exam, your doctor may perform several tests and procedures^[1].

Your doctor will do a pelvic exam and ask about your medical history and any problems you’re having^[2]. During a pelvic exam, the doctor or nurse inserts one or two lubricated, gloved fingers of one hand into the vagina and places the other hand over the lower abdomen to feel the size, shape, and position of the uterus and ovaries. The vagina, cervix, fallopian tubes, and rectum are also checked^[1].

You will probably get an ultrasound. This test uses sound waves to make pictures of your ovaries. It can show tumours on your ovaries^[2]. An ultrasound exam is a procedure in which high-energy sound waves are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram^[1]. Your provider may insert an ultrasound wand into your vagina (called a transvaginal ultrasound) to detect tumours in the ovaries^[5].

If you have a tumor on one ovary, your other ovary should be checked, too. An ultrasound can show the size of the tumor and whether it has spread to nearby tissues^[2].

You may also get other imaging tests, such as CT scans and MRIs. These can show more details. Your doctor can use them to see if the tumor has spread^[2]. A magnetic resonance imaging (MRI) scan is an advanced imaging test that provides detailed pictures of your ovaries and helps doctors determine if a tumour is benign, malignant or borderline^[5].

A blood test called CA 125 assay measures the level of CA 125, a substance released by cells into the bloodstream^[3].

If these tests show that you have a tumour, a biopsy is the only way to know if it’s cancer^[2]. A biopsy is the primary method to diagnose a borderline ovarian tumour. Most biopsies for borderline ovarian tumours are performed during surgery. Doctors examine biopsied tumour cells under high-resolution microscopes to determine the correct diagnosis, which will then guide treatment^[5]. Sometimes all of the tumour is taken out and then checked for cancer^[2].

Borderline tumours are difficult masses to correctly diagnose before surgery using imaging methods because their appearance may overlap with invasive and benign ovarian tumours^[4]. Borderline tumours often share ultrasound findings with malignant tumours including papillary projections, thickened septations, and multicystic components. However, a significant percentage of borderline tumours present as unilocular cysts on ultrasound^[7].

Outlook and survival

Tumours of low malignant potential account for 15% of all epithelial ovarian cancers. Nearly 75% of these tumours are stage I at the time of diagnosis^[8]. These tumours must be recognized because their prognosis and treatment is clearly different from the frankly malignant invasive carcinomas^[8].

Borderline ovarian tumours have an excellent prognosis. A review of 22 series including 953 patients with a mean follow-up of 7 years revealed a survival rate of 92% for patients with advanced-stage tumours. The cause of death was determined to be benign complications of disease (such as small bowel obstruction), complications of therapy, and only rarely (0.7%), malignant transformation^[8].

In one series, the 5-, 10-, 15-, and 20-year survival rates of patients with low malignant potential tumours (all stages) were 97%, 95%, 92%, and 89%, respectively^[8]. In this series, mortality was stage dependent: 0.7%, 4.2%, and 26.8% of patients with stages I, II, and III, respectively, died of disease^[8].

Another large study showed early stage, serous histology, and younger age to be associated with a more favorable prognosis^[8]. In general, patients with this disease have a good prognosis for recovery^[3].

The pathological stage of disease and subclassification of extraovarian disease into invasive and noninvasive implants, together with the presence of postoperative macroscopic residual disease, appear to be the major predictor of recurrence and survival^[4]. However, symptomatic recurrence and death may be found as long as 20 years after therapy in some patients^[4].

Treatment options

Surgery is the recommended management for borderline ovarian tumours^[7]. For nearly all borderline tumours, surgery is the only treatment needed, even when borderline tumours have spread to other areas^[5].

Your doctor will recommend a treatment plan that depends on several factors^[2]:

• Your tumour’s size
• Whether it has spread beyond the ovary
• Whether you want to get pregnant
• Your age
• Your general health
• Your choices

Surgery to take out the affected ovary is the most common treatment. Surgery may involve removing the mass alone or the affected ovary and fallopian tube^[5]. If you don’t plan any more pregnancies, your surgeon may remove both ovaries, the fallopian tubes, uterus, and cervix, too. This is called a hysterectomy^[2].

The choice between a laparoscopic or open approach is based on the size of the mass, as well as prior surgical history and experience of the primary surgeon. A laparoscopic approach is reasonable and preferred in most patients with a focus on avoiding spillage^[7]. Whenever possible, doctors use minimally invasive (laparoscopic) surgery that is performed through smaller incisions. This approach typically results in a faster recovery, minimal scarring and a reduced risk for post-surgical complications as compared to a traditional open surgical procedure^[5].

If you might still want to get pregnant, your doctor may be able to take out only the affected ovary and the fallopian tube on the same side^[2]. In young patients, fertility-sparing surgery or preservation of an unaffected ovary to avoid surgical menopause is often possible^[5]. Fertility-sparing surgical management of borderline ovarian tumours in patients who desire future fertility is preferred, and should be planned unless the patient decides otherwise. Patients under 40 who prefer to avoid the symptoms and effects of surgical menopause can also be offered conservative surgery^[7].

Sometimes, you may be able to have just the tumour taken out and the ovary is left in place, but this is rare^[2]. Relapse rates of up to 15% have been noted with unilateral oophorectomy (removal of one ovary) and up to 30% with unilateral cystectomy (removal of just the tumour), but relapse is typically borderline rather than malignant and is highly curable with reoperation^[7].

Most gynecologic surgeons diagnose a borderline ovarian tumour either with intraoperative frozen section or on final operative pathology^[7]. During surgery, peritoneal washings should be performed prior to pelvic mass excision, and the mass should be excised intact without spillage into the peritoneal cavity^[7]. The pelvis and abdominal organs need to be carefully inspected to exclude any visible invasive disease, and suspicious areas must be biopsied^[7].

If the tumour has spread beyond the ovary to nearby tissues, your doctor will remove as much of it as possible^[2]. The tumours can spread to other parts of your body, like your lungs and liver, but this does not happen often^[2].

In some situations, endocrine (hormone) therapy after surgery may be considered^[5]. If the tumour is cancer, your doctor will talk to you about more chemotherapy treatment^[2]. Surgery and chemotherapy are the most common treatment options for patients with ovarian low malignant potential tumour^[3].

Tissue removed during surgery will be reviewed by expert gynecologic pathologists to confirm an accurate diagnosis. Information from the pathologist’s report will guide an individualized follow-up plan that is tailored to your needs^[5].

Follow-up care

After surgery, you will need to see your doctor about every 6 months so you can be checked for signs that the tumour has come back^[2]. Patients with borderline ovarian tumours will need to continue long-term follow-up^[5].

The most important negative prognostic factor for recurrence is the use of conservative surgery, but without any impact on patient survival because most recurrent diseases are of the borderline type—easily curable and with an excellent prognosis^[4].

In the event that only a cystectomy is performed and final pathology results are consistent with borderline tumour, a gynecologic oncologist can counsel the patient regarding possible reoperation to remove the affected adnexa with possible surgical staging versus surveillance^[7].