Pathological complete response: what it means

Pathological complete response, often shortened to pCR, means that when tissue is removed during surgery after pre-surgery treatment, the pathologist examining it under a microscope finds no remaining invasive cancer cells in the area where the tumour was, and usually none in the glands removed. It applies when chemotherapy, sometimes with targeted treatment, immune treatment or radiotherapy, is given before an operation. This approach is used in several cancers, including some breast cancers, rectal cancer, oesophageal and stomach cancers, bladder cancer and some head and neck cancers. Pathological complete response is different from complete response on a scan, because the microscope can see far smaller amounts of cancer than any scan can.

Pathological complete response matters for two main reasons. First, in several cancers, research has linked it with a lower chance of the cancer returning compared with people who still have cancer in the removed tissue. This is especially studied in some types of breast cancer, where it is used as an important measure of how well pre-surgery treatment worked. Second, the pathology result can change what happens next. For example, in some breast cancers, people who still have cancer remaining after pre-surgery treatment may be offered additional treatment after surgery, while those with pCR may continue the originally planned treatment.

It is important to understand the limits. Pathological complete response is an encouraging result, but it does not rule out the cancer returning, because cancer cells may exist elsewhere in the body. Its meaning also varies between cancer types and subtypes. Not achieving pCR does not mean treatment failed; many people with remaining cancer in the tissue still do very well, especially with further treatment. Your oncologist and surgeon will explain your pathology report and what it means for your next steps. This page explains the term; it cannot interpret your own report.

It is found after surgery

Only examination of removed tissue can show pathological complete response.

It can shape further treatment

The pathology result may change what is recommended after surgery.

Not achieving it is not failure

Many people with some remaining cancer still have good results with further treatment.

It cannot interpret your pathology report or tell you what your result means for your future. Pathology reports contain detailed terms and measurements, and your oncologist and surgeon will explain them.

It also cannot give figures about outcomes linked to pathological complete response. These vary between cancers and subtypes and should be discussed with your oncologist.

Near-complete and partial pathological response

Pathology reports often describe how much cancer remains, using terms such as near-complete response, residual disease, or a tumour regression score. These describe degrees of response rather than a simple yes or no. Your oncologist uses this detail to plan further treatment.

Why pCR is used in research

Because pathological complete response can be measured soon after treatment, researchers use it in clinical trials to compare pre-surgery treatments. This has helped identify more effective approaches for some cancers.

Waiting for pathology results

Pathology results usually take some days after surgery, sometimes longer if extra tests are needed. The wait can be stressful, especially while recovering from an operation. Ask when and how results will be discussed.

Watch-and-wait approaches

In some rectal cancers, when scans and examinations after treatment show no visible cancer, a small number of people may be offered close monitoring instead of immediate surgery in specialist centres. This is a specialised decision that needs careful discussion.

Emotional reactions

Hearing that no cancer was found can bring enormous relief, while hearing that some remains can be disappointing. Both reactions are natural. Ask for support if you need it.

Keeping your report

Keep a copy of your pathology report with your treatment summary for future care.

How pathologists examine tissue

The removed tissue is measured, sliced and examined under the microscope. Pathologists look at the area where the tumour was, the edges of the removed tissue and any glands. They look for remaining cancer cells and for signs of treatment effect, such as scarring. Special stains may be used. This detailed work is why results take some days.

Surgical margins

Pathology reports also describe margins, which is whether cancer cells reach the edge of the removed tissue. Clear margins mean no cancer at the edge. Your surgeon will explain what your margins mean for any further treatment.

Pathological response in breast cancer

In breast cancer, pathological complete response usually requires no invasive cancer in both the breast and the glands under the arm. A small amount of non-invasive cancer may still be present, and your team will explain whether it affects the plan.

Pathological response in rectal cancer

In rectal cancer treated with chemotherapy and radiotherapy before surgery, pathology reports often describe how much cancer remains. This helps guide decisions about further chemotherapy.

Further treatment after pCR

Even after pathological complete response, some planned treatment may continue, such as targeted treatment, hormone treatment or radiotherapy, depending on the cancer. Completing these is important.

Team review of results

Pathology results are often discussed at a team meeting of surgeons, oncologists, pathologists and radiologists. Ask whether your case has been reviewed and what the team recommends.

Keeping perspective

Whatever the pathology result, focus on the plan ahead and on recovery from surgery. Your team will guide the next steps.

What to do next

Ask when pathology results will be available, what your result shows, how it affects further treatment, and what follow-up is planned; keep a copy of your report; and report any problems after surgery promptly.