Treatments for adenocarcinoma of unknown primary

The following are treatment options for adenocarcinoma of unknown primary. Your healthcare team will suggest treatments based on your needs and work with you to develop a treatment plan.

When deciding which treatments to offer for adenocarcinoma of unknown primary, your healthcare team will consider:

• the amount of differentiation of the cancer cells
• whether it is favourable-risk or poor-risk
• where and how many different places cancer is found
• prognosis
• performance status
• where the cancer may have started (called the primary site)
• your overall health
• your age
• your preferences for treatment

Favourable-risk adenocarcinoma is identified based on where the cancer is found in the body and based on biopsy results. The following favourable-risk adenocarcinoma:

• adenocarcinoma of unknown primary in the lymph nodes under the arm in women
• adenocarcinoma in the lining of the abdomen (called the peritoneum) in women
• cancer that has spread to the bone in men who have a high prostate-specific antigen (PSA) level
• one tumour in the liver, lung, brain or in another organ
• adenocarcinoma of unknown primary of colorectal type

The type of chemotherapy offered for adenocarcinoma of unknown primary will depend on where the cancer is found.

If diagnostic tests suggest that the cancer may have come from a specific part of the body, your healthcare team may offer chemotherapy for that type of cancer. This could include chemotherapy for colorectal cancer or chemotherapy for non–small cell lung cancer.

When women have adenocarcinoma of unknown primary in the lymph nodes under the arm, it is possible that the breast is the primary site. So they will be given drugs used to treat breast cancer. Doctors will test the cancer cells to find out their HER2 status. Women who have a HER2-positive cancer may also be offered trastuzumab (Herceptin). Find out more about chemotherapy for breast cancer and HER2 status testing.

The adenocarcinoma of unknown primary in the lining of a woman’s abdomen may have started in the ovary. Women with this cancer will be treated with chemotherapy for epithelial ovarian cancer.

If you have poor-risk or undifferentiated adenocarcinoma of unknown primary and doctors don’t have a best guess for where it started, your healthcare team will offer the type of chemotherapy that they think will work best. This is referred to as empirical chemotherapy. They will usually give 2 or more drugs. Most drug combinations include at least one of the following:

• a platinum drug – either cisplatin (Platinol AQ) or carboplatin (Paraplatin, Paraplatin AQ)
• a taxane drug – either paclitaxel (Taxol) or docetaxel (Taxotere)
• gemcitabine  (Gemzar)

The most common combination used is carboplatin (as it has fewer severe side effects) and paclitaxel.

External beam radiation therapy may be offered for adenocarcinoma of unknown primary.

Men who have adenocarcinoma of unknown primary in the bone and a high prostate-specific antigen (PSA) level may have cancer that started in the prostate. Radiation therapy may be given to bones to relieve pain, shrink the tumours and help prevent the bones from breaking.

Women who have adenocarcinoma of unknown primary in lymph nodes under the arm may be offered radiation therapy for breast cancer after surgery. The radiation may be directed where the lymph nodes were removed and to the breast on the same side of the body.

Hormonal therapy is a treatment that adds, blocks or removes hormones. The type of hormonal therapy offered will depend on where the cancer is found.

Women who have adenocarcinoma of unknown primary in the lymph nodes under the arm will be treated with hormonal therapy for breast cancer.

Men who have cancer in the bone and a high prostate-specific antigen (PSA) level will be treated with hormonal therapy for prostate cancer.

Doctors may offer surgery if there is only one tumour that can be completely removed. The type of surgery will depend on where the tumour is in the body.

Surgery is also offered in women with cancer found in the peritoneal cavity or who have cancer in the lymph nodes under the arm.

You may want to consider a type of care to make you feel better rather than treat the cancer itself. This may be because the cancer treatments don’t work anymore, they’re not likely to improve your condition or they may cause side effects that are hard to cope with. There may also be other reasons why you can’t have or don’t want cancer treatment.

Talk to your healthcare team. They can help you choose care and treatment for advanced cancer.

You may be asked if you want to join a clinical trial for cancer of unknown primary. Find out more about clinical trials.