What should you know about IHC for lung cancer?

Immunohistochemistry, or IHC, is performed on tissue obtained during a [Biopsy](/treatments/diagnostics-and-staging/biopsy/). In the laboratory, selected antibodies are applied to thin tissue sections. If a target marker is present, the tissue develops a stain that a pathologist examines under a microscope.

The pattern may help distinguish lung cancer from another cancer that has spread to the lung, and may help classify a lung cancer subtype. Some markers provide information relevant to immunotherapy or other treatments. IHC is one part of the diagnosis; it is interpreted alongside the biopsy appearance, scans, symptoms, and sometimes [Genomic Tumour Profiling](/treatments/diagnostics-and-staging/genomic-tumour-profiling/).

Ask whether the report names the tissue tested, the markers examined, and whether each result is positive, negative, or indeterminate. A result is meaningful only in its clinical context, and a single marker does not describe the whole cancer or predict exactly how an individual will respond.

Keep a copy of the pathology report and ask whether more tissue is needed for additional tests. Treatment may involve surgery, [Radiotherapy](/treatments/radiation-oncology/radiotherapy/), [Chemotherapy](/treatments/systemic-therapy/chemotherapy/), immunotherapy, or a combination. The result may also be discussed if symptoms such as [Hoarse Voice](/symptoms/hoarse-voice/) need assessment.

IHC itself does not usually create new symptoms because it is performed on stored biopsy tissue. Contact your clinical team if the biopsy site becomes increasingly painful, red, swollen, or draining, or if you develop fever after the procedure. Seek urgent help for severe breathlessness, coughing blood, fainting, or rapidly worsening chest pain.

Which markers were tested, and what does each finding mean for my diagnosis? Is the sample large enough for genomic testing? How will the IHC result affect treatment options, and when will the full pathology review be available?