Introduction: Who Should Undergo Diagnostics

If you have been treated for adenosquamous cell lung cancer in the past, it is important to stay alert for signs that the disease may have returned. Recurrent cancer means the cancer has come back after a period when tests showed no evidence of disease. Anyone who has completed treatment for adenosquamous lung cancer should work closely with their healthcare team to monitor for recurrence, even if they feel completely well.^[1]

You should seek diagnostic evaluation if you notice symptoms such as a persistent cough that doesn’t go away, chest pain, shortness of breath, coughing up blood, unexplained weight loss, or unusual fatigue. These symptoms can also occur in people without cancer recurrence, but they warrant medical attention if you have a history of lung cancer. Sometimes recurrent adenosquamous carcinoma does not cause noticeable symptoms in its early stages, which is why regular follow-up appointments and scheduled testing are essential parts of your care plan.^[1][17]

People who have been treated with surgery, chemotherapy, or radiation for adenosquamous lung cancer are at risk for recurrence. Research shows that after surgical removal of adenosquamous carcinoma, the cancer can return in some patients. In one study, out of 176 patients who had surgery to completely remove their adenosquamous lung cancer, 95 experienced disease recurrence during follow-up. The rates of recurrence were approximately 26% at one year, 56% at three years, and 63% at five years after surgery.^[3]

Certain factors can increase the likelihood of recurrence. If your original tumor was at a more advanced stage when first diagnosed, if cancer cells were found in blood or lymphatic vessels (a condition called lymphovascular invasion), or if lymph nodes tested positive for cancer, your risk of recurrence may be higher. Understanding these risk factors helps both you and your healthcare team decide how frequently you need diagnostic testing.^[3]

Diagnostic Methods for Identifying Recurrent Disease

Diagnosing recurrent adenosquamous cell lung cancer involves several types of tests that help doctors determine whether the cancer has come back, where it is located, and how extensive it might be. These diagnostic tools work together to provide a complete picture of what is happening in your body.

Imaging Tests

Imaging tests create pictures of the inside of your body and are typically the first step in detecting recurrent cancer. A chest X-ray is a simple test that uses radiation to create an image of your lungs and can reveal abnormal masses or nodules. While chest X-rays are useful for initial screening, they may not show small tumors or provide enough detail for a definitive diagnosis.^[5]

A computed tomography scan, commonly called a CT scan, provides much more detailed images than a standard X-ray. During a CT scan, a machine moves around your body taking multiple pictures from different angles, which a computer then combines to create cross-sectional images of your chest. CT scans are more sensitive than X-rays and can detect smaller abnormalities in the lungs, lymph nodes, or other areas where cancer might have spread.^[5]

Positron emission tomography, or PET scan, is another imaging technique that can identify areas where cancer cells are actively growing. Before the test, you receive an injection of a small amount of radioactive sugar solution. Cancer cells, which grow and divide rapidly, absorb more of this sugar than normal cells do, causing them to “light up” on the scan images. PET scans are particularly helpful for determining whether suspicious areas seen on CT scans are actually cancer and for identifying cancer that has spread to distant parts of the body.^[5]

Magnetic resonance imaging, or MRI, uses powerful magnets and radio waves instead of radiation to create detailed images of soft tissues. MRI scans are especially useful for examining the brain to check whether lung cancer has spread there. Some patients with recurrent lung cancer may need brain MRIs as part of their diagnostic workup.^[5]

Biopsy Procedures

While imaging tests can suggest that cancer has returned, a biopsy is usually needed to confirm the diagnosis. A biopsy involves removing a small sample of tissue from a suspicious area so it can be examined under a microscope by a pathologist. This examination determines whether cancer cells are present and, if so, what type of cancer they represent.^[5]

Adenosquamous carcinoma is particularly challenging to diagnose because it contains a mixture of two different types of cancer cells: adenocarcinoma cells (which form in gland-like structures) and squamous cell carcinoma cells (which are flat and scale-like). For a definitive diagnosis of adenosquamous carcinoma, the tissue sample must show that at least 10% of the tumor consists of each cell type. Because of this mixed nature, different biopsy samples from the same tumor might yield different results, which is why larger tissue samples are often more reliable.^[1][4]

There are several ways to obtain a biopsy. Bronchoscopy is a procedure where a thin, flexible tube with a small camera on the end is passed through your nose or mouth, down your throat, and into your airways. The doctor can see inside your lungs and use small instruments passed through the bronchoscope to collect tissue samples from suspicious areas. Bronchoscopy is particularly useful when the suspicious area is located in or near the airways.^[5]

Needle biopsy involves using a thin needle to remove tissue from a lung mass or lymph node. This procedure is often guided by CT scanning or ultrasound to ensure the needle reaches the correct location. Needle biopsies are less invasive than surgical biopsies and can often be performed as an outpatient procedure.^[5]

In some cases, particularly when the recurrence is in hard-to-reach areas or when other biopsy methods haven’t provided enough tissue, surgical biopsy may be necessary. Video-assisted thoracic surgery (VATS) allows surgeons to insert small instruments and a camera through small incisions in the chest wall to obtain larger tissue samples while causing less trauma than traditional open surgery.^[1]

Laboratory Tests

Various laboratory tests support the diagnostic process for recurrent adenosquamous lung cancer. Blood tests cannot directly diagnose lung cancer recurrence, but they can provide valuable information about your overall health and organ function. Some blood tests measure specific substances called tumor markers that cancer cells may release into the bloodstream. For adenosquamous carcinoma, markers such as CEA (carcinoembryonic antigen) may be elevated when cancer is present or recurring.^[3]

Immunohistochemical testing, often called IHC testing, involves treating biopsy tissue samples with special stains or antibodies that attach to specific proteins on cancer cells. These tests help pathologists identify what type of cells are present and can help distinguish between different types of lung cancer. For adenosquamous carcinoma, pathologists look at markers that indicate both adenocarcinoma features (such as TTF1, Napsin A, or CK7) and squamous features (such as p63 or CK5/6) to confirm the mixed nature of the tumor.^[3]

In addition to confirming the diagnosis, immunohistochemical tests can identify specific characteristics of your cancer cells that influence treatment decisions. For example, testing for PD-L1 protein expression helps determine whether you might benefit from certain immunotherapy medications. In one study of adenosquamous carcinoma, PD-L1 expression was found in 11% of the adenocarcinoma component and 28% of the squamous component of these tumors.^[13]

Molecular and Genetic Testing

Molecular testing examines the genetic material (DNA) inside cancer cells to look for specific mutations or changes that drive cancer growth. This type of testing has become increasingly important because it can identify patients who may benefit from targeted therapies—medications designed to attack cancer cells with specific genetic changes while causing less harm to normal cells.

For recurrent adenosquamous carcinoma, doctors typically test for mutations in the EGFR gene (epidermal growth factor receptor). EGFR mutations are present in approximately 30% of adenosquamous carcinomas. When these mutations are found, patients may respond to medications called EGFR tyrosine kinase inhibitors, such as erlotinib, gefitinib, or osimertinib.^[1][13]

Another important genetic change to test for is ALK rearrangement, which occurs in about 5% of adenosquamous carcinomas. Patients with this genetic alteration may benefit from targeted therapy with medications like crizotinib.^[13]

Testing may also identify mutations in other genes such as p53, which is found in approximately 25% of adenosquamous carcinomas. While no targeted therapies currently exist for p53 mutations, this information helps doctors understand the biology of your specific cancer.^[13]

Diagnostics for Clinical Trial Qualification

If you are considering participation in a clinical trial for recurrent adenosquamous lung cancer, you will likely need additional or more extensive diagnostic testing than what was required for your initial diagnosis. Clinical trials have specific eligibility criteria that help ensure the study can answer important scientific questions and that participants can safely receive the experimental treatment being studied.

Pathological Confirmation

Nearly all clinical trials require pathological confirmation that you have adenosquamous carcinoma. This means biopsy tissue must be reviewed by a pathologist who confirms the presence of both adenocarcinoma and squamous cell carcinoma components. Some trials may require that tissue samples be sent to a central pathology laboratory for review to ensure consistent diagnosis across all study participants.

Because adenosquamous carcinoma can change over time, clinical trials often require a recent biopsy rather than relying solely on tissue from your original diagnosis. When cancer recurs, the recurrent tumor may have different genetic characteristics than the original tumor, so fresh tissue sampling provides the most current information about your disease.^[4]

Staging and Disease Assessment

Clinical trials typically require thorough staging to determine the extent of your cancer recurrence. Staging describes how far cancer has spread in the body and uses a system of numbers and letters to categorize the disease. Complete staging usually involves multiple imaging tests such as CT scans of the chest and abdomen, PET scans, and brain MRI to identify all areas where cancer is present.

Different clinical trials enroll patients at different disease stages. Some studies focus on patients with localized recurrence (cancer that has returned in or near the original site), while others enroll patients with metastatic recurrence (cancer that has spread to distant organs). Your staging results determine which trials you might be eligible to join.^[5]

Molecular Profiling

Many modern clinical trials for lung cancer focus on specific molecular subtypes of the disease. These trials often require comprehensive molecular testing before enrollment. This testing examines your tumor tissue for a panel of genetic mutations and biomarkers that might predict response to the study treatment.

For adenosquamous carcinoma, important tests for clinical trial eligibility include EGFR mutation testing, ALK rearrangement testing, and PD-L1 expression testing. Some trials specifically enroll patients whose tumors have particular genetic characteristics, while others may exclude patients with certain mutations if those patients have better treatment options available outside of the trial.^[1][2]

Performance Status and Organ Function

Clinical trials assess your overall health and ability to carry out daily activities using something called performance status. Doctors evaluate whether you can care for yourself, how much time you spend in bed or a chair during waking hours, and whether you can perform light work. Most clinical trials only enroll patients who are relatively healthy and active, as they are more likely to tolerate experimental treatments safely.

Laboratory tests measuring kidney function, liver function, and blood cell counts are standard requirements for clinical trial participation. These tests ensure your organs are working well enough to process and eliminate the study medication and that you have sufficient blood cells to tolerate treatment. Abnormal results in these tests might make you ineligible for certain trials or require dose adjustments if you do enroll.

Prior Treatment Documentation

Clinical trials need detailed information about all previous treatments you have received for your cancer. This includes what types of chemotherapy, radiation therapy, immunotherapy, or targeted therapy you received, the dates of treatment, your response to those treatments, and any significant side effects you experienced. Some trials specifically enroll patients who have received certain prior therapies, while others exclude patients who have had particular treatments.

For recurrent adenosquamous carcinoma, the number of prior treatment lines matters for many clinical trials. A treatment line refers to a complete course of therapy given to treat your cancer. Some trials enroll only patients who have received one or two prior treatment lines, while others focus on patients whose cancer has progressed despite multiple previous treatments.^[9]