Lung cancer offers non-specific symptoms that, in addition, usually appear when the disease has already spread. There is no suspicious lump or blood in the stool that could raise the first alarm, as in breast or colon cancer. This is why only one in four such cancers is diagnosed at an early stage, when they can still be removed by surgery. But there are early diagnosis techniques and screening that could improve the prognosis.
“When it is still localized, it can only be detected through an imaging test,” explains Dr. Margarita Majem, doctor attached to the Medical Oncology Service at the Santa Creu i Sant Pau hospital in Barcelona. “And this imaging test is either obtained by chance, that is, because the patient has it done for any other reason, or you have to go look for it.”
“Going for it” means identifying people who are most likely to have lung cancer and giving them a test to confirm or rule it out. This is what is known as population screening, a strategy to detect the disease at an early stage. “To do this, we must first know which people are at greater risk of suffering from it, even if they do not yet have symptoms,” says Dr. Laureano Molins, consultant at the Thoracic Surgery Service at the Hospital Clínic of Barcelona and national coordinator of the Lung Ambition Alliance.
Tobacco, the main culprit
In the case of lung cancer, this greater risk is in the group of smokers or ex-smokers. Tobacco is responsible for around 80%-90% of cases and, therefore, the main preventable cause. As Dr. Molins indicates, “it is evident that we must work on primary prevention, but we have been warning smokers to stop smoking for 45 years and we are still very far away, since one in four people in our country still smokes. If we want to improve survival, early diagnosis is essential.”
This is how the lung cancer screening strategy arises. “At the Clínica Universidad de Navarra, we have been working for 20 years within the I-ELCAP, an international screening program for lung cancer,” explains Dr. Luis Seijo, director of the clinic’s Department of Pulmonology. “We have published the results of almost 90,000 people, detecting more than 1,200 cancers. Screening increases survival, and that is why practically all scientific societies defend it,” says the coordinator of the Thoracic Oncology area of the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR).
To carry it out, the test recommended by clinical guidelines is low-radiation dose computed tomography (LDCT), which is normally known as low-dose CT. Randomized trials of BDCT screening have shown significant reductions in lung cancer mortality and have triggered international efforts to implement screening. “There is evidence of its effectiveness. It just needs to be put into action, so that political decision-makers can see the benefits of screening,” explains Dr. Seijo.
In this sense, the European Commission has published its recommendations in this regard as a commitment to act in a coordinated manner against cancer, highlighting the importance of carrying out pilots for the subsequent implementation of lung cancer screening throughout the European Union.
The situation in Europe regarding the implementation of lung cancer screening at the population level is very variable. The governments of Poland, Croatia and Italy have committed to implementing a lung cancer screening program in high-risk people, with the first two being in very advanced stages. Countries such as the United Kingdom, Sweden and Germany are exploring the viability of its implementation, while France, Belgium, the Netherlands and Spain are in a preliminary evaluation phase.
The Cassandra project
In this context, the Cassandra Project arises, promoted by the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR) to demonstrate the viability of screening in our country. This multicenter and multidisciplinary program incorporates TCBD as a screening tool and aims to provide the necessary evidence so that this system for early detection of lung cancer can be implemented in our health system. SEPAR has the support of nine scientific societies, two patient associations and entities committed to the fight against this disease.
Although the project was born with the intention of launching in 14 autonomous communities, and in November 2023 it was announced that it would be carried out in more than 40 hospitals throughout Spain, at the moment only three hospitals in Madrid and three in Barcelona have already patient recruitment started. The Aragon Health Department has already given its approval, and SEPAR is finalizing an agreement with the Andalusian Health Service to incorporate all Andalusian hospitals.
Recruitment in Madrid and Barcelona is the first link in a chain that includes smoking cessation and secondary prevention. As Dr. Majem indicates, “defining inclusion criteria can be controversial.” In breast cancer, all women of an age and older feel concerned; In the colon, the possibility is offered to men and women also from an age. “But in lung cancer it is different: first you have to identify the candidates, then offer it to them and they agree to do it. The adhesion [el cumplimiento del programa por parte de los pacientes] In some countries it is low, but that doesn’t mean you’re going to stop trying.”
Regarding the inclusion criteria, American guidelines recommend offering it to people over 50 years of age who smoke or have smoked a pack of tobacco a day for at least 20 years and to ex-smokers who have not smoked for more than 15 years. Even so, these criteria leave out the 15% of patients who develop lung cancer without ever having smoked. Its early detection is a problem still unsolved. “There is no way to identify them,” acknowledges Dr. Molins.
The cost of CT
The other obstacle is the cost. Dr. Molins points out, from his experience, that a low-dose CT scan is twice as expensive as a mammogram. It is a biased vision, Molins points out: “If we manage to operate and cure 80% of the patients who are diagnosed with cancer in the initial phase, the cost of chemotherapy, radiotherapy and immunotherapy will be saved. Aside from the ethical dilemma: How much is a saved life worth?” And Dr. Seijo adds: “You need to do 800 mammograms to detect breast cancer. In the lung, you detect one or two in every 100 scans. In the end, it is a cheaper tool.”
Low-dose CT also detects non-malignant lesions. This is the case of lung nodules, explains Dr. Lola Lozano, director of the Department of Pathological Anatomy at the Clínica Universidad de Navarra and president-elect of the Spanish Society of Pathological Anatomy (SEAP), who explains that, given this finding, “it is can biopsy to assess what we are facing and take the appropriate therapeutic measures. “This is about avoiding unnecessary surgeries and toxicities.”
Primary and secondary prevention
An issue that is always put on the table when talking about lung cancer is the reconciliation between primary prevention, that is, that aimed at avoiding the disease, and secondary prevention, that in which an attempt is made to detect this disease early to prevent it. reduce its impact on health.
The first case would be to get people not to smoke; The second is to detect the tumor in time, explains Dr. Majem: “Both strategies must go hand in hand. Through screening, lives can be saved in the short term. But working to prevent people from smoking or quitting will have an impact on health in 20 years. And you have to work on it.”
In this sense, Dr. Seijo points out that Cassandra links primary prevention with secondary prevention: “Tobacco not only causes lung cancer, but also cardiovascular diseases, COPD, and other types of cancer. And furthermore, you can use the information that the CT scan gives you to be more convincing when it comes to mentalizing the patient.”
Predictive biomarkers
One more point of work in the approach to lung cancer is that of biomarkers. “A biomarker is a biological characteristic that can be objectively measured and evaluated as an indicator,” explains Dr. Lozano. “Pathologists diagnose the disease, the type and subtype of cancer, and biomarkers can give us very valuable predictive information that can help us predict how a patient will respond to a specific treatment.”
Predictive biomarkers “are undergoing great development in certain types of tumors, such as breast and lung tumors.” However, the role of non-image-based early detection biomarkers “is still in an early research phase,” concludes the doctor.