How is cancer of unknown primary treated?

Cancer of unknown primary means cancer has been found, often in a lymph node or another organ, but the place where it started has not been identified after initial assessment. Doctors review biopsy findings, examine the cells under a microscope, and use scans such as PET-CT to look for a source. Genomic tumour profiling may identify features that suggest which medicines could help, even when the original site remains unclear.

Treatment depends on where the cancer is found, how widely it has spread, the cancer cell type, symptoms, and general health. Chemotherapy or another systemic medicine may treat cancer throughout the body. Surgery or radiotherapy may be used for a particular area causing symptoms or posing a local risk. Sometimes the plan is based on a pattern that resembles a known cancer, while other cases need broader cancer control and supportive care.

Keep copies of biopsy reports and scan results, and ask which tests are still needed before treatment begins. Tell the team about previous cancers, family history, medicines, allergies, weight change, pain, and new lumps or swelling. Discuss the purpose and timing of each test, whether a genomic result will change treatment, and how side effects will be managed. Nutrition, pain relief, emotional support, and practical help can be part of the plan from the start.

Seek urgent care for severe breathlessness, chest pain, new confusion, sudden weakness, uncontrolled bleeding, inability to keep fluids down, or rapidly worsening pain. Contact the oncology team quickly for fever during treatment, a new painful swelling, or a marked decline in function.

What did the biopsy show about the cancer cells? Which primary sites are being considered? Will PET-CT or genomic tumour profiling change the treatment choice? What is the goal of chemotherapy or another medicine? Which symptoms require same-day advice?