Discussion
Tuberculosis (TB) is an infectious disease caused by the Mycobacterium
tuberculosis complex, characterized by granulomas with caseous necrosis.
In contrast, lung cancer is a malignant tumor resulting from genetic
mutations due to various factors leading to abnormal cell proliferation.
According to studies conducted in China, the incidence of TB can
increase the risk of developing lung cancer[6]. It has been found
that in pulmonary TB lesions of mice, most squamous cells exhibit
abnormally high proliferative activity[7]. Cytokines produced from
TB infection, such as TGF-β and IL-10, have immunosuppressive
properties, which can enhance the incidence of tumors[8]. During the
progression of lung cancer, cytokines like IL-4, IL-10, and TGF-β1 are
produced. These factors assist in TB evasion from immune
detection[9]. Moreover, some studies suggest that TB dissemination
may occur during clinical lung cancer immunotherapy, but the precise
mechanisms still require further investigation[10]. Compared to
patients with only lung cancer or TB, those afflicted by both conditions
have a shorter average survival period, with even shorter life
expectancy for those with active TB[11].
The clinical symptoms of both lung cancer and TB have many similarities.
In this case, the patient primarily presented with symptoms of coughing
and hemoptysis, which are nonspecific. The gold standard for diagnosing
TB is a positive sputum culture for Mycobacterium tuberculosis, although
the positivity rate is relatively low[12]. At this juncture,
radiographic examinations are crucial for both diagnosis and
differential diagnosis. CT scans have a high accuracy rate, over 90%,
in diagnosing concurrent TB and lung cancer, with common signs including
pleural adhesions, pleural retraction, bronchial narrowing, and
bronchial obstruction[13]. However, CT scans have a lower
specificity for fibrotic changes due to benign lesions, leading to
frequent false-positive results[14]. There have been numerous recent
reports on the diagnostic use of MRI for thoracic diseases, where MRI
can predict changes in TB lesions based on T2 signal intensity[15].
In recent years, 18F-fluorodeoxyglucose positron emission
tomography-computed tomography (18F-FDG PET/CT) imaging has been widely
confirmed for the specific diagnosis of malignant tumors[16].
However, due to its high cost and radiation, it is not suitable for
screening lung cancer combined with TB. Ultimately, diagnoses of both
lung cancer and TB should be confirmed through etiology and
histopathology.
There have been some clinical reports on lung cancer concurrent with
pulmonary tuberculosis [17,18], but the number remains limited. The
majority of patients face the choice between anti-tuberculosis treatment
and anti-tumor therapy. Over 80% of lung cancer patients are diagnosed
in the intermediate or advanced stages, with the main treatment
approaches being concurrent or sequential radiotherapy, chemotherapy,
and targeted therapy. Literature has reported poor prognoses for
patients with lung cancer and concurrent tuberculosis post-surgical
treatment. Smoking history, irritative cough, TNM staging, and the
presence of prior tuberculosis lesions have all been identified as risk
factors for non-small cell lung cancer patients with active tuberculosis
[19]. There is also literature documenting cases of lung
adenocarcinoma patients with EGFR mutations treated with afatinib in
combination with anti-tuberculosis therapy. Studies indicate that the
combination of erlotinib and anti-tuberculosis treatment can effectively
control both tuberculosis and the tumor [18].
This paper reports a case of a patient with squamous cell carcinoma of
the lung concurrent with pulmonary tuberculosis, who declined genetic
mutation testing. Radiotherapy is a commonly used local treatment for
malignant tumors. Compared to chemotherapy, its toxic effects on the
patient’s liver, kidney functions, blood, gastrointestinal tract, and
respiratory system are relatively less. Therefore, we opted for
concurrent radiotherapy for lung cancer during the intensive phase of
tuberculosis treatment. During the intensive phase of tuberculosis, a
combination of four drugs is typically used. Isoniazid is primarily
metabolized through the acetylation reaction mediated by NAT2, while
rifampin is predominantly deacetylated to form acetylated rifampin. The
combined use of these two drugs increases hepatotoxicity[20]. In
this report, the patient chose rifapentine capsules, which ensures
effective treatment concentrations while reducing side effects[21].
Ethambutol is mainly metabolized in the liver and excreted through the
kidneys. Compared to isoniazid and rifampicin, its hepatotoxicity is
minimal[22]. Aminoglycosides, such as streptomycin, kanamycin, and
amikacin, are primarily metabolized in the kidneys. Among them,
streptomycin has a high ototoxicity, but its nephrotoxicity is lower
than other aminoglycosides. These drugs exhibit concentration-dependent
bactericidal effects; hence, reducing drug dosage is not recommended to
prevent an increased risk of drug resistance[23]. Quinolones, like
ofloxacin and moxifloxacin, are metabolized in the body through both
liver and renal pathways, with approximately 52% through the liver and
45% through the kidneys[23]. During the patient’s anti-tuberculosis
treatment and radiotherapy, we continuously monitored their complete
blood count, liver and kidney functions, and electrolytes, and no
abnormalities were observed.
The patient entered the consolidation phase of combined therapy, during
which two or three drugs are typically administered in tandem. The
treatment regimen was adjusted to rifapentine capsules, isoniazid
tablets, and ethambutol. At this stage, the anti-tuberculosis
treatment’s impact on liver and kidney functions is relatively minor.
Considering the patient’s upcoming chemotherapy phase, after
consultation with the pharmacy department, we opted for a treatment
scheme with paclitaxel and carboplatin. Paclitaxel acts by stabilizing
microtubules, thus inhibiting tumor cell division. It is primarily
metabolized in the liver via CYP2C8 and CYP3A4, different from the
metabolism pathway of tuberculosis drugs. However, liver functions still
need to be stringently monitored during treatment. Platinum-based drugs
play a crucial role in lung cancer chemotherapy. Compared to cisplatin,
carboplatin has higher solubility, reduced toxicity, no nephrotoxicity,
and reduced ototoxicity[24]. Considering the patient’s financial
situation, we selected this regimen. Throughout the treatment, we
closely monitored the patient’s liver and kidney functions and blood
routine. The patient demonstrated good tolerance and did not experience
any adverse reactions.
In conclusion, the patient underwent combined treatment for tuberculosis
and lung cancer. Upon evaluation, therapeutic results were observed for
both diseases, with significant lesion reduction. However, when treating
patients with concurrent lung cancer and pulmonary tuberculosis, the
selection of an appropriate treatment plan should consider the patient’s
specific circumstances. How to effectively treat both diseases
simultaneously to enhance patient survival remains an area we need to
further explore.
Informed consent
Written informed consent was obtained from the patient to publish this
report in accordance with the journal’s patient consent policy.