Incidental finding of renal cell carcinoma in an asymptomatic patient on low-dose computed tomography screening for lung cancer

KEYwords: Early detection of cancer/methods; incidental findings; kidney neoplasms; renal cell carcinoma; quaternary prevention; early detection of cancer/economics; primary care physicians; low-dose computed tomography.

As preventive medicine improves, diseases that were once death sentences are now becoming preventable. For example, tobacco-associated lung cancer treated with pharmaceuticals only prolongs life by a few months, but smoking cessation can prolong life by years. Despite a 70% decline in adult tobacco use, lung cancer remains the leading cause of cancer-related mortality (>25%) in the United States. Lung cancer screening with low-dose computed tomography (LDCT), when compared to chest radiographs, reduces lung cancer mortality by 20% and all-cause mortality by 7%.¹

In 2013, the United States Preventive Services Task Force (USPSTF) recommended annual LDCT lung cancer screening in adults aged 55–80 years with a significant history of smoking.² This increased LDCT screening has incited concern about incidental findings identified on these scans, most of which are benign, and the potential cost and worry incurred by patients while investigating them. Across multiple studies, 79–94% of LDCTs were positive for an incidental finding; of these, 7–15% warranted further testing or treatment.³

Common findings include cardiovascular disease, chronic obstructive pulmonary disease (COPD), interstitial lung disease, and extra-pulmonary neoplasms. Although screening tests are covered by insurance in the United States and are therefore widely available, other health-care systems do not readily fund such testing, so heavy consideration must be given to the potential benefits and detriments of screening if such practices are to be adopted elsewhere.

Here, we report a case of papillary renal cell carcinoma detected incidentally on LDCT in an asymptomatic individual who received curative treatment with partial nephrectomy.

A 70-year-old man with a 45 pack-year history of smoking underwent a LDCT scan of the chest for screening purposes. The scan showed a 3-mm nodule in the left lower lobe, which was indeterminate and did not warrant further follow up, as well as an indeterminate right renal mass (Figure 1). The patient had no complaints of haematuria, flank pain, or family history of kidney tumours. His history was significant for hypertension, adult-onset diabetes, benign prostatic hyperplasia, glaucoma, and COPD.

Figure 1.  Low-dose computed tomography (a) frontal view: arrowhead indicates the exophytic upper pole right renal mass; (b) transverse view: arrowhead indicates the exophytic upper pole right renal mass.

Renal ultrasound showed an exophytic, solid-appearing, anterior upper pole mass of the right kidney. A right partial nephrectomy was performed, excising a 5.6-cm mass that was confirmed by pathology to be papillary renal cell carcinoma (Type 1). The patient’s kidney function remained stable 5 years post-operative. Annual LDCT screenings in the 6 years since treatment have shown no signs of metastatic disease.

Renal cell carcinoma (RCC) represents 2–3% of all adult cancers and is the most common primary kidney cancer. Papillary RCC, seen in our patient, is the second most common type, accounting for 10–20% of all kidney cancers. Our patient’s papillary RCC was a type 1, Fuhrman nuclear grade 2, confined to the renal capsule, without renal vein invasion, with no indication of recurrence in 5 years following removal. Survival in patients with RCC found before invasion of the urinary collecting system is >90% over 10 years; however, cancers found after invasion have a 10-year survival as low as 41%.⁴ Given that this patient did not have any urinary complaints beyond those expected with his history of benign prostatic hyperplasia, it is unlikely his RCC would have been discovered this early without the incidental finding on LDCT lung cancer screening.

Early diagnosis of neoplasm improves patient outcomes, so the value of early diagnosis may become increasingly recognised as LDCT is more widely adopted. Although LDCT lung cancer screening does meet the Wilson and Jungner criteria for a beneficial exam, screening is not without risks. Patients face increased lifetime radiation exposure from repeated annual scans, increasing risk of cancer development. Furthermore, benign incidental findings are common and undue burden on patients and health-care systems can result.³ This further testing may also expose the patient to needless worries, associated costs, and the risk of complications from further biopsies and testing.⁵ The increased utilisation of specialist services that may result from workup of incidental findings has been associated with potential adverse effects on overall health outcomes.⁶

Because of these concerns, the adoption of screening practices emphasises the role of primary care providers in quaternary prevention, working to protect their patients from unnecessary medical interventions and treatments. Considering that many of the most commonly identified incidental findings, such as COPD and cardiovascular disease, require preventive treatment or maintenance, increased use of screening practices may increase the burden of ongoing interventions borne by primary care providers. However, early detection reduces progression, symptoms, and improves the management options that are available for patients with COPD, limiting morbidity and mortality and improving patients’ quality of life. Although incidental findings may increase the number of patients with known disease, catching disease early improves patient health and limits the financial cost associated with treating later stage disease.⁷

The debate regarding the risks and benefits of screening is not unique to lung cancer screening. The USPSTF has assigned an ‘A’ or ‘B’ recommendation, indicating at least moderate certainty of benefit from screening, to 52 screening practices, including breast cancer, diabetes, and sexually transmitted infection screening. In 2018, the USPSTF evaluated the benefits and risks of LDCT screening for lung cancer and updated their recommendation to begin screening at age 50 years, rather than 55 years, and to include people with at least a 20 pack-year smoking history, rather than 30.

As screening practices and recommendations continue to be adopted and revised, clinicians need to be vigilant about current best practices and the implications for patients and health-care providers, including potential investigation of incidental findings. Here, we present a case of an asymptomatic papillary renal cell carcinoma that was incidentally found on LDCT lung cancer screening and was treated with nephrectomy. Fortunately, this patient’s treatment was successful, and this experience prompted lifestyle changes including a reduction in his tobacco use, weight loss to manage his diabetes, and compliance with further cancer screenings. This case demonstrates the importance of careful consideration of incidental findings, as well as the potential risks and benefits for patients undergoing various screening procedures.

The authors have no competing interests to report regarding the contents of this manuscript.

This report did not receive any specific funding.

Data sharing is not applicable as no new data were generated or analysed during this study.