What is Prophylactic Cranial Irradiation (PCI)?

Indications and Side Effects of PCI for People with Lung Cancer

scanner in radiation therapy department
What is prophylactic cranial irradiation (PCI)?. istockphoto.com

Definition: Prophylactic Cranial Irradiation (PCI)

Prophylactic cranial irradiation (PCI) for people with lung cancer is a preventative radiation therapy to the head to kill cells that may have already spread there but are unable to be seen yet with scans. PCI is used most commonly with small cell lung cancers that have responded to initial treatment with chemotherapy and radiation therapy.

Why PCI?

Small cell lung cancer has a strong tendency to spread to the brain, and sometimes the first symptoms of small cell lung cancer are related to that spread.

It's been found that radiation treatments delivered to the head before any evidence of spread can significantly decrease this complication. When radiation is used in this way, a lower dose of radiation is given than if radiation were being used to treat brain metastases from lung cancer.

People with small cell lung cancer often respond very well, at least initially, to chemotherapy. In this setting, oncologists talk about the brain being a "high rent district." The goal is to prevent brain metastases since brain metastases significantly lower the quality of life for people with lung cancer due to symptoms such as seizures.

When is Prophylactic Cranial Irradiation (PCI) Used?

PCI is used when someone with small cell lung cancer has no evidence of spread to the brain on imaging studies, but there is a reasonable chance that the cancer will spread in time. It is most commonly used for people with limited-stage small cell lung cancer, but may also be used for people with extensive stage small cell lung cancer.

How is it Given?

PCI is given as external beam radiation while you lie on a table.  It only takes a few minutes for the treatment and is not painful. People usually have radiation daily, 5 days a week for up to 3 weeks.

Side Effects of Prophylactic Cranial Irradiation (PCI)

Side effect of radiation to the brain may include:

  • Hair loss - Unlike hair loss from chemotherapy, hair loss from radiation therapy to the head may be permanent.
  • Fatigue - Fatigue is the most common side effect of radiation therapy and tends to get worse over the course of treatment.
  • Redness - A sunburn-like rash may appear on your face and scalp.
  • Cognitive changes - Some of the more annoying symptoms of prophylactic radiation to the head include memory loss, confusion, and headaches.
  • Nausea and vomiting.
  • Loss of appetite.
  • Weight loss.

Long Term Side Effects of Prophylactic Cranial Irradiation (PCI)

It's been found in recent years that PCI can cause permanent cognitive problems (brain damage) in people who go through this treatment, especially in those who have this treatment combined with platinum-based chemotherapy drugs such as Platinol (cisplatin.) Due to the high likelihood of brain metastases with small cell lung cancer, this therefore often comes down to weighing the risks and benefits for each individual considering the procedure.

How Will You Know if PCI Worked?

There are a few ways in which you will know if PCI has worked. The most obvious is that it's less likely that you will develop symptoms of brain metastases than if you did not have PCI.

The other way is through imaging tests to look for evidence of metastases. These are scheduled at different times for different people depending on a host of different factors.

Pronunciation: pro-ful-ak-tik kray-ne-ul ir-fay-dee-ay-shun

Also Known As: PCI

Examples: Sam was given prophylactic cranial irradiation to kill any lung cancer cells that may have spread to his brain, but were too small to be seen on his brain CT scan.


Simo, M., Vaquero, L, Ropolles, P. et al. Brain damage following prophylactic cranial irradiation in cancer survivors. Brain Imaging and Behavior. 2015 May 17. (Epub ahead of print).

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