What Are B Symptoms in Carcinoma?
B symptoms are a specific triad of constitutional symptoms—unexplained fever >38°C, drenching night sweats requiring change of clothes/bedding, and unexplained weight loss >10% of body weight within 6 months—that are classically associated with lymphomas but are NOT typically referred to as "B symptoms" in solid organ carcinomas. 1
Definition and Origin of the Term
The term "B symptoms" originates from lymphoma staging systems and has a precise clinical definition:
- Fever: Temperature >38°C without identifiable infectious cause 1
- Night sweats: Drenching sweats that require changing clothes or bedding 1
- Weight loss: >10% of body weight lost unintentionally within 6 months 1
The presence of these symptoms adds the letter "B" to the lymphoma stage (e.g., Stage IIB), while their absence is denoted by "A" (e.g., Stage IIA). 1
Clinical Context: Lymphomas vs. Carcinomas
In Lymphomas (Where the Term Applies)
- B symptoms indicate systemic involvement and more advanced disease in Hodgkin lymphoma and aggressive non-Hodgkin lymphomas 2, 1
- They are critical staging criteria and treatment triggers, particularly in follicular lymphoma where their development mandates therapy initiation 1
- B symptoms are part of high tumor burden criteria in follicular lymphoma 1
- In HIV-associated Hodgkin lymphoma, B symptoms are common but may also indicate concurrent opportunistic infection if CD4 counts are low 2
In Solid Organ Carcinomas (Where the Term Does NOT Apply)
Important caveat: While patients with solid tumors like breast, renal, or other carcinomas may experience fever, night sweats, or weight loss, these are not formally called "B symptoms" in oncology terminology. 3, 4
- Advanced cancer patients are polysymptomatic, with constitutional symptoms being common but not classified as "B symptoms" 3, 4
- In advanced cancer across 17 primary sites, pain, fatigue, and anorexia are consistently among the most prevalent symptoms 3
- Weight loss >10% is common in advanced carcinomas but is simply termed "cachexia" or "cancer-associated weight loss," not a "B symptom" 4
Rare Paraneoplastic Presentations
- Fever can rarely be a presenting symptom of metastatic breast carcinoma as a paraneoplastic syndrome, sometimes with elevated interleukin-6 and interleukin-1 receptor antagonist concentrations 5
- Such presentations are exceptional and should not be confused with the formal "B symptoms" terminology used in lymphomas 5
Clinical Significance
The key distinction: If you are evaluating a patient with a solid organ carcinoma (breast, lung, colon, renal, etc.) who has fever, night sweats, or weight loss, these are constitutional symptoms that warrant investigation but should not be documented as "B symptoms" in the medical record, as this terminology is reserved for lymphomas and would cause confusion. 1, 3