Lung Cancers: Facts, Causes, and Types

Between 1999 and 2014, lung cancer was the leading cause of cancer-related deaths in the United States and the third most prevalent type of cancer in the country.^1,2

EPIDEMIOLOGY

In 2017, lung cancer is projected to be the second most prevalent type of cancer in the United States, with about 222,500 new cases and is estimated to still be the leading cause of cancer-related death, with 155,870 deaths (see figure).² This would make up 13.2% of all new cancer cases and 25.9% of all deaths caused by cancer in 2017.² From 2007 to 2013, the percentage of patients who survived lung cancer for 5 years was 18.1%, which decreased from 19.6% in 2009.²

Table 1^1,2 illustrates the breakdown of lung cancer cases by the stage of cancer, as well as the 5-year relative survival for each group.

Table 2^1,3,4 highlights the risk factors linked to increased lung cancer incidence. Tobacco smoking remains the leading cause of lung cancer, despite the overall decline in smoking among both genders.¹

Non—small cell lung cancer (NSCLC), small cell lung cancer (SCLC), and mesothelioma are among the most common types of lung cancer. There are also a few less prevalent lung cancer types that originate in the lung and chest wall. Most rare lung cancers are secondary to metastasis. These lung cancer types vary according to size, rate of metastasis, and recommended treatment options.⁵ See table 3^3,6 for the prevalence and characteristics of the various subcategories of lung cancer. NSCLC is the most common type of lung cancer and is further characterized by the histology of cells involved. NSCLC is relatively unresponsive to chemotherapy and/or radiation treatment, compared with SCLC.⁶

In general terms, risk factors such as smoking may cause damage to the epithelial cells that line the bronchioles. This damage causes the host’s normal repair system to activate to remove damaged cells and replace them with new, healthy cells. The repair system is inactivated when the restoration process is complete. The network of enzymes involved in this process may not activate or may not recognize the cells as being abnormal, thus allowing for continuation of tumor cell replication, which may eventually spread beyond where it originated. Depending on the type of enzymes involved, this may be a slow or rapid process. Lung cancer may metastasize to distant organs, and tumors originating in breast tissue or in the pancreas can disseminate to the lungs.^3,5

SCREENING

Lung cancer is the second most prevalent type of cancer, behind breast cancer.² Lack of standard screening contributes to a poor prognosis, as the disease is not identified until it has progressed to more advanced stages.^3,5 Genetic screening has played a role in diagnosis, especially in patients who are nonsmokers.³ Annual screening with low-dose computed tomography imaging is recommended to identify lung cancer in high-risk individuals,^3,4 as it is more sensitive for detecting lung cancer than chest radiography.⁴ However, several studies are evaluating the optimal frequency and duration, as well as the impact of false-positive tests.³

PREVENTION

Over the past several decades, many campaigns have been conducted to curb tobacco use and discourage children from ever starting the habit. The development of lung cancer in non-smokers paralleling that of active tobacco users led to the ban of smoking in public areas. Furthermore, there has been increased recognition of the emotional and physical toll on those who attempt to stop smoking. This has prompted the development of state programs offering free smoking-cessation counseling to those who are ready to quit but need help because of failed attempts or to those who need guidance on available products.³

TREATMENT

Treatment decisions are guided by the stage of disease, which is characterized by tumor size, metastasis, and histology. Patient-specific factors, such as performance status or comorbid conditions, must also be considered when developing a treatment plan.³ The treatment goal in lung cancer is to cure it in early-stage disease, whereas in advanced disease, the goals become to prolong survival and improve the quality of life.

Early-stage lung cancer has the highest cure rates when surgical resection of the tumor is performed with or without chemotherapy for NSCLC and chemoradiotherapy for SCLC.^3,6,7 In earlier stages of NSCLC, the treatment options can be based on the staging of the disease: local disease (stage I or II) and locally advanced disease (stage III).^3,6 Table 4^3,6-8 illustrates the treatment options for the early stages of lung cancer, based on the progression of the disease.

Advanced-stage lung cancer, classified as NSCLC stage IIIB and IV or extensive and recurrent disease in SCLC, is treated primarily with systemic therapy.³ The tumors in these patients are not surgically resectable, and the focus of care is on improv- ing quality of life, attenuating symptoms, and increasing the length of survival.³ Advanced-stage NSCLC is further divided into 4 treatment subgroups, based on the histologies involved. Doublet platinum-based chemotherapy regimens are superior in response to single-agent regimens and should be used when the patient can tolerate the associated toxicity.³ Platinum-containing doublets are first-line treatment in most cases.³ Targeted therapies for advanced-stage NSCLC are preferred over platinum-based doublets, as first-line therapy in those patients whose tumors express certain genetic mutations, such as epidermal growth factor receptor exon 19 deletions or exon 21 (L858R) substitution mutations or anaplastic lymphoma kinase—positive mutations.³ Immunotherapy with an anti—programmed death 1 monoclonal antibody is approved for the second-line treatment of NSCLC and is a novel therapeutic class of oncology treatment available for these patients.³ Table 5^3,6-8 lists the therapies used for treating advanced stages of NSCLC and SCLC and their place in therapy.

HEALTH CARE PROFESSIONAL’S ROLE

The patient deserves an involved, integrated, interdisciplinary team to facilitate health care and end-of-life decisions. This team should consist of a minimum of an oncologist, a mid-level practitioner, a pharmacist, a nurse, a hospice worker, and a social worker. Clinicians trained in end-of-life decisions should be used to discuss the patient’s wishes for terminal care. Metastatic lung cancer may be managed, but the long-term sur- vival numbers are a stark reality. Based on this discussion, the interdisciplinary team should assist the patient in achieving real- istic health care goals while optimizing the patient’s quality of life. The goals of this team should be to mitigate the symptoms of the disease, connect the patient with health care resources, and manage the adverse effects of drug therapy.

CONCLUSION

As new research is targeted toward specific biomarkers and genetic traits, it is hoped that patients’ outcomes will improve. Greater personal responsibility by the patient must be assumed to reduce risk factors, and cancer screenings must be improved to decrease the number of lung cancer deaths. It is rewarding as a clinician to see improvement in the longevity and quality of patients’ lives by effective disease state management.

Jerry A. Barbee Jr, PharmD, BCPS, CPh, and Glenn Schulman, PharmD, MS, BCPS, BCACP, BCGP, are clinical pharmacists at HCA West Florida Hospital.

Catherine M. Kew and Emily V. Olivier are PharmD candidates at Auburn University.

References

1. United States cancer statistics: 1999-2014 cancer incidence and mortality data. Centers for Disease Control and Prevention website. cdc.gov/uscs. Accessed October 9, 2017.

2. Cancer stat facts: lung and bronchus cancer. National Cancer Institute website. seer.cancer.gov/statfacts/html/lungb.html. Accessed October 9, 2017.

3. Adams VR, Peters SS. Lung cancer. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill Medical; 2017;chap 129.

4. Lung cancer screening (PDQ)-health professional version. National Cancer Institute website. www.cancer.gov/types/lung/hp/lung-screening-pdq. Updated September 29, 2017. Accessed October 9, 2017.

5. Lung cancer types. hopkinsmedicine.org/healthlibrary/conditions/adult/respiratory_disorders/respiratory_disorders_22,LungCancerTypes/. Johns Hopkins Medicine website. Accessed October 9, 2017.

6. Non-small cell lung cancer treatment (PDQ)-health professional version. www.cancer.gov/types/lung/hp/non-small-cell-lung-treatment-pdq. National Cancer Institute website. Updated March 31, 2017. Accessed October 9, 2017.

7. Detterbeck FC, Lewis SZ, Diekemper R, Addrizzo-Harris D, Alberts WM. Executive summary: diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2013;143(suppl 5):7S-37S. doi: 10.1378/chest.12-2377.

8. Wu K, Wong E, Chaudhry S. Lung cancer. McMaster Pathophysiology Review. 2011;32(4):605-44. http://pathophys.org/lung-cancer/#Pathogenesis.