High-risk human papillomavirus (HR-HPV) types are responsible for almost all cases of
cervical cancer, as well as several cancers of the head, neck, penis, vulva, and anus.
Like many other small-genome viruses, HPV (~8 kb) uses various mechanisms,
including alternative splicing, to increase its genome’s capacity to encode the proteins
necessary for successfully completing its infectious life cycle.In recent years, much
research has focused on the activities and roles of E6 proteins from HR-HPVs during
the process of cellular transformation, identifying E6 as a key player in this process.
However, the role of the smaller splice isoform, E6*, in carcinogenesis is not yet fully
understood. Based on previous studies, we proposed that E6* has the potential to
reduce tumor formation in vivo.To test this hypothesis, we injected HPV16+ (SiHa) and
HPV16- (C33A) cervical cancer cells overexpressing E6* into nude mice, monitored
tumor growth over several weeks, and compared it to control tumors lacking E6*
expression. The results showed that E6* reduced tumor growth in cells derived from
both SiHa and C33A. These findings were supported by in vitro assays, demonstrating
that E6* binds to full-length E6 and slows growth in SiHa cells.We then sought to
identify the cellular pathways influenced by E6* in reducing tumor growth in SiHa and
C33A cells. Proteomic analysis was conducted on both cell lines, revealing that the β-
integrin pathway showed the most significant changes in SiHa cells, while mitochondrial
dysfunction and oxidative phosphorylation pathways were most altered in C33A cells.
The proteomic data were validated using immunoblotting, microscopy, and flow
cytometry.These findings contribute to our understanding of the key drivers behind HPV-
mediated and non-HPV-mediated cervical cancers and introduce new ideas for
developing small-molecule inhibitors. Our studies also provide several promising leads
for future investigations, particularly in the context of human cancers, and open the
possibility of replicating the anti-oncogenic activity of E6* in a way that could offer
therapeutic benefits
This chapter provides an overview of cervical cancer and the role of human
papillomavirus (HPV) as an oncogene in regulating this type of cancer. Cervical cancer
is one of the most common types of cancer among women and can be asymptomatic in
its early stages. As the disease progresses, symptoms may include abnormal vaginal
bleeding, foul-smelling discharge, impaired bladder or bowel function, and leg
edema.Human papillomavirus is primarily transmitted through mucosal contact with
virus-infected areas, including the anus, mouth, or vagina. Transmission may occur via
saliva, semen, or contact with the skin of an infected partner during intercourse. HPV
infection typically occurs during or immediately after sexual contact when the mucosal
surface becomes vulnerable to infection.A hallmark of cancer is tumor-associated
inflammation, which becomes especially apparent in the later stages of the disease.
Current treatments for HPV infections are mainly surgical, including excision,
cryotherapy ablation, laser therapy, or electrosurgical procedures. Additionally, some
non-surgical interventions, such as topical gels or creams, are available and widely
used to treat genital warts.In conclusion, a better understanding of HPV’s role in cervical
cancer and the development of new therapeutic approaches could help reduce the
burden of this disease and improve the lives of patients battling cervical cancer..
High-risk human papillomaviruses (HR-HPVs) are recognized as the primary causative
agents of various malignancies in the genital and oropharyngeal regions. Specifically,
about 70% of cervical and oropharyngeal cancers are attributed to HPV types 16 and
18. These viruses not only cause cancer on their own, but certain other viruses, such as
herpes simplex virus (HSV), Epstein-Barr virus (EBV), and human immunodeficiency
virus (HIV), also interact with HPV. These interactions may significantly influence the
replication and persistence of HPV and the progression of cancer.
HPV infection can be markedly affected by co-infectious agents, which influence the
dynamics of the infection and disease progression. For example, concurrent bacterial
infections, such as Chlamydia trachomatis, along with species associated with bacterial
vaginosis, in the genital tract can interact with HPV, leading to the persistence of the
virus and adverse disease outcomes.These co-infections involving HPV and various
infectious agents can have significant implications for disease transmission and clinical
progression. Therefore, it is crucial to examine and understand the multiple aspects of
HPV infection, including the dynamics of co-infections with other pathogens, interactions
with the human microbiome, and their role in disease development. This analysis helps
researchers and clinicians devise better strategies for preventing and treating HPV
infections and their related consequences.
Psychological stress has been recognized as a significant factor in the persistence and
increased severity of HPV infections, eventually contributing to cancer progression. In
response to stress, the hypothalamic-pituitary-adrenal (HPA) axis is activated, leading to
the secretion of glucocorticoids, such as cortisol. These hormones increase oxidative
stress by promoting DNA damage and generating reactive oxygen species (ROS) and
reactive nitrogen species (RNS), causing DNA damage and impairing the immune
system.Studies have shown that psychological stress can prolong HPV infections and
reactivate latent viruses. Stress also weakens the body’s antiviral immunity, potentially
enhancing the expression of HPV oncogenes and facilitating immune evasion. In
women with cervical dysplasia, stress is associated with reduced T-cell function and a
weakened immune response to HPV16, which may accelerate cancer
progression.Chronic stress exposure, by elevating cortisol levels and shifting the
immune response from Th1 to Th2, reduces natural killer (NK) cell activity and
increases the risk of HPV-related infections and cancer. Various studies have found that
individuals with higher levels of stress exhibit a greater prevalence of HPV infections
and a delay in viral clearance.Chronic stress can also increase the expression of viral
proteins like HPV-E6, while decreasing miR-145 levels, leading to impaired p53 function
and greater resistance to chemotherapy. Furthermore, stressful lifestyles and
psychological disorders such as depression and bipolar disorder have been linked to a
heightened risk of HPV-related cancers, including cervical cancer.In summary,
psychological stress can increase the risk of HPV-related cancers by affecting the
immune system and enhancing oxidative stress. This connection suggests that stress
management and lifestyle improvements could play a crucial role in preventing and
slowing the progression of HPV-related cancers.
HPV infection is recognized as a key risk factor for cancer, but it plays an even more
significant role when interacting with complex mechanisms such as oxidative stress
(OS). Oxidative stress, triggered by lifestyle choices like smoking, alcohol consumption,
and even psychological stress, contributes to DNA damage and promotes
tumorigenesis in HPV-related cancers. HPV accelerates cancer development through
various mechanisms, including mitochondrial alterations, increased levels of reactive
oxygen species (ROS), DNA damage, and suppression of antioxidant
pathways.Moreover, HPV-infected cells adapt to oxidative stress by inhibiting apoptosis
and inducing changes in DNA repair pathways. This allows the virus to enhance its
survival and promote carcinogenesis. The virus’s ability to exploit oxidative stress and
damage cellular defenses further drives the progression of HPV-related cancers.
Oxidative Stress: A Cofactor in HPV-Related CarcinogenesisOxidative stress (OS) has
been identified as a key factor in HPV-related carcinogenesis. Numerous studies
confirm elevated OS levels in malignant cells, primarily due to oncogenic mutations and
metabolic changes. These disruptions lead to increased metabolic activity, hypoxia,
overexpression of growth factors, and excessive production of reactive oxygen species
(ROS), all of which contribute to heightened OS in malignant cells. ROS act as
secondary messengers in intracellular signaling processes, promoting the survival and
persistence of cancer cells. Interestingly, malignant cells exhibit greater resistance to
OS compared to normal cells.
HPV’s Adaptation to Oxidative Stress
HPV demonstrates an ability to adapt to oxidative stress by enhancing protective
mechanisms, such as the upregulation of superoxide dismutase (SOD) and catalase
(CAT) in infected cells. The key mechanisms enabling cancer cells to survive OS involve
the regulation of antioxidant activity and suppression of OS-induced apoptosis. These
processes are controlled by HPV oncogenes, particularly E7, which allows uncontrolled
proliferation of infected cells.Experimental Evidence and the Impact of Oxidative Stress
on CarcinogenesisA study by Di Marco and colleagues demonstrated increased OS in
samples from women with dysplastic or neoplastic cervical lesions. Dysplastic samples
exhibited OS-induced changes in proteins such as cytoskeletal keratin 6 and
glyceraldehyde 3-phosphate dehydrogenase. Conversely, better control of OS was
observed in cancerous samples, highlighting OS’s role in creating a favorable
environment for malignant transformation.Oxidative Stress Markers and Immune
ResponseThe microenvironment of malignant cells is characterized by elevated levels
of OS biomarkers. Romano and colleagues found higher levels of 8-hydroxy-2’-
deoxyguanosine in dysplastic cells compared to normal cells, indicating OS’s crucial
role in carcinogenesis. Additionally, Naidu et al. discovered a positive correlation
between malondialdehyde (MDA) levels and lesion severity in cervical cancer
patients.Siegel et al. proposed that OS markers could reflect the host’s immune
response to HPV infection. In a study of 444 HPV-positive women, they found that
higher levels of two OS biomarkers were associated with faster clearance of oncogenic
HPV types, suggesting a complex interaction between oxidative burden and viral
persistence.The Role of Antioxidants In Cervical Cancer:A deficiency in certain
antioxidants may influence the progression of HPV infection. Antioxidants can modulate
the expression of AP-1 transcription factors, which play a role in regulating the
oncogenic proteins E6 and E7. Another study by Manju and colleagues revealed lower
levels of key antioxidant enzymes such as GPx and SOD, along with reduced levels of
vitamins C and E, in cervical cancer patients.Vitamin and Antioxidant Intake in Cervical
Cancer:Antioxidant vitamins can neutralize free radicals that damage DNA, potentially
making cells more susceptible to HPV infection. Meta-analyses have shown that intake
of vitamins B12, E, and beta-carotene is associated with a protective effect against
cervical cancer. Notably, a study by Myung and colleagues found that the consumption
of vitamins E and beta-carotene was linked to a reduced risk of cervical
neoplasia.Overall, the available evidence highlights the pivotal role of oxidative stress
and disrupted antioxidant balance in HPV-related carcinogenesis, emphasizing the
importance of vitamin and antioxidant intake in the prevention of these cancers.
The Impact of Genetic and Environmental Factors on HPV Infection and Cancer
Progression
Multiple factors contribute to the progression of cervical cancer caused by HPV
infection, extending beyond the viral factors themselves. Genetic susceptibility to
infection, increasing host age, as well as epigenetic factors and lifestyle choices such as
smoking, chronic inflammation, and concurrent infections with other sexually transmitted
organisms, particularly Chlamydia trachomatis, can significantly increase the risk of
cancer progression in women infected with HPV. These factors are associated with
increased oxidative stress and DNA damage.
Oxidative Stress and DNA Damage
Extensive DNA damage typically leads to apoptosis; however, in HPV-infected cells, the
viral oncogenes E6 and E7 can evade this pathway, resulting in mutagenesis and
enhanced cellular proliferation. Oxidative stress is recognized as a significant factor in
cellular transformation and can arise during viral infection due to immune responses to
viral proteins or the expression of viral genes. This stress leads to oxidative DNA
damage and may facilitate the integration of HPV DNA.
The Effect of Oxidative Stress in Viral Infections
Research has shown that oxidative stress induced by viral infections such as EBV, HCV,
and HBV leads to DNA damage and cellular transformation. For example, in HBV and
HCV infections, the accumulation of mutated proteins and chronic infection is
characterized by increased oxidative stress. In the case of EBV and nasopharyngeal
cancer, oxidative stress is stimulated by the lytic life cycle and viral oncogenes.
Characteristics of HPV and Oxidative Stress
In HPV infections, the host immune response is usually limited, and the virus itself does
not induce chronic inflammation, as it infects basal epithelial cells that protect against
circulating immune cells. However, reactive oxygen species (ROS) and reactive
nitrogen species (RNS) can play significant roles in viral carcinogenesis. For instance,
exposing HPV16-infected cells to reactive nitrogen species increases the levels of E6
and E7 while also heightening DNA damage.
E6 and E6* Isoforms
HPV16 E6 is expressed in two main isoforms: a full-length isoform (E6) and several
truncated isoforms, generally referred to as E6*. While the activities of E6 have been
extensively studied, less information is available regarding the E6* isoform. These
truncated isoforms may play important roles in the viral life cycle and carcinogenesis.
The Effect of E6* on Oxidative Stress
In the current study, it was determined that E6*, rather than E6, can increase ROS
levels and lead to DNA damage. Altering the ratio of E6 isoforms can change ROS
levels such that an increased ratio of E6* consistently elevates oxidative stress.
Additionally, studies indicated that the truncated E6 isoforms might regulate the
expression of enzymes related to ROS metabolism, thereby increasing DNA damage
levels.
Materials and Methods:In this study, various monoclonal antibodies were used to
investigate the role of E6 and E6* in oxidative stress and DNA damage. These
antibodies included anti-superoxide dismutase isoform 1 (SOD1) and anti-glutathione
peroxidase (Gpx), which were obtained from reputable companies. Conclusion:The
findings of this study indicate that the truncated isoforms E6* play a significant role in
increasing oxidative stress and DNA damage and may contribute to a better
understanding of the mechanisms underlying HPV-induced carcinogenesis. Identifying
and better understanding these mechanisms could aid in the development of new
therapies and preventive strategies against HPV infections and their complications.
Immune Evasion in HPV Infection, Squamous Intraepithelial Lesions (SIL), and Cervical
Cancer
Human papillomavirus (HPV) evades the immune system by altering the host’s immune
response, consequently contributing to the development of squamous intraepithelial
lesions (SIL) and cervical cancer. These mechanisms include the downregulation of
interferon expression and the modulation of immunosuppressive cytokines such as
interleukin-10 (IL-10) and transforming growth factor-beta 1 (TGF-β1).
1. Immune Evasion Mechanisms
Downregulation of Interferon Expression: HPV prevents the activation of the immune
response by reducing interferon production, which plays a key role in the immune
response to infections.
Regulation of IL-10 and TGF-β1: These two cytokines obstruct the antitumor immune
response by creating a locally immunosuppressive environment. The presence of IL-10
and TGF-β1 in high-risk HPV infections and SIL may create conditions that negatively
impact the cellular immune response (Sasagawa et al., 2012; Torres-Poveda et al.,
2014).
2. Effects on SIL and Cervical Cancer
Creation of an Immunosuppressive Microenvironment: This microenvironment can lead
to viral persistence and the progression of cervical cancer. Studies have shown that
high levels of IL-10 and TGF-β1 are correlated with the severity of lesions in patients
with SIL and cervical cancer (Bermudez-Morales et al., 2008).
Mechanisms of Immune Suppression: Local immune suppression in cervical cancer is
dependent on Th2 and Th3 cytokines. In this context, a pattern of immunosuppressive
cytokine expression has been identified in cancerous tissues that is absent in normal
tissues (Shiv et al., 2001; Alcoser-Gonzalez et al., 2006).
3. The IL-10 and TGF-β1 Feedback Loop
4. Mutual Reinforcement of Expression: IL-10 and TGF-β1 help to enhance each
other’s expression and promote the production of HPV-16 E6 and E7 proteins.
These proteins induce the genes for TGF-β1 and IL-10, creating a feedback loop
(Peralta-Saragoza et al., 2006).
Reduction of CD3 Expression: IL-10 and TGF-β1 reduce CD3 expression, which is
essential for T cell activation. This mechanism ultimately leads to the recruitment of
regulatory T cells (Tregs) and the establishment of a tolerogenic environment, which
aids in immune evasion.
5. Importance of These Findings:These findings are crucial not only for
understanding how HPV evades the immune response but also for the
development of HPV vaccines and targeted immunotherapies for women with
LGSIL, HGSIL, and cervical cancer (Peralta-Saragoza et al., 2012).
Future Questions
As research progresses, more questions have emerged regarding the immune
response to HPV infection and cervical cancer. Studies have shown that T lymphocytes
in patients with cervical lesions and cancer are only partially activated, and the
expression levels of signaling molecules are diminished.
1. Investigation of Th1 Cytokines: Researching whether Th1 cytokines can
counteract the expression of these molecules is of particular importance.
2. Production of HPV-Specific T Lymphocytes: Efforts to generate fully functional
HPV-specific T lymphocytes could enhance immunotherapeutic treatments and
cervical cancer prevention.
Conclusion
HPV contributes to the development of SIL and cervical cancer through diverse
mechanisms of immune evasion. Understanding these mechanisms may lead to the
creation of more effective therapeutic approaches to combat this infection and its
consequences.
HPV Infection and Its Consequences
HPV Infection and Progression to Neoplasia
A minority of individuals, estimated to be between 10% and 20%, are unable to effectively clear
HPV infection and persistently harbor the viral DNA in their bodies. These individuals are at risk
for progression to cervical intraepithelial neoplasia (CIN2/3) and ultimately invasive cancer.
HPV infections are primarily epithelial in nature, and the virus likely infects basal epithelial cells
at low copy numbers. In the early phase of replication, the number of nuclear episomes in each
cell increases to 100 or more. During the episome maintenance phase, the virus remains in the
epithelium with minimal viral gene expression.
Viral gene expression peaks in the upper layers of the epithelium (1/3 – 2/3) and is accompanied
by the synthesis, assembly, and shedding of viral capsids limited to these layers. This replication
strategy, with tight control of early gene expression, prevents the expression of the strong
oncogenic characteristics of E6 and E7 proteins of high-risk HPVs in dividing cells. However, if
the viral infection becomes persistent, the risk of molecular events that dysregulate E6 and E7
expression in mitotically active cells increases, potentially leading to the initiation of neoplastic
progression.
HPV Immune Evasion Strategies
HPV effectively evades detection by the immune system. The infectious cycle itself provides a
mechanism for this evasion. The virus expresses very low levels of viral proteins and does not
act as a cytolytic virus. Viral replication and assembly occur in cells that have already been
designated for death, meaning there is no inflammation or danger signals to alert the immune
system.
The interferon response, which is a key antiviral defense mechanism, is actively suppressed by
HPV E6 and E7 proteins. These proteins contribute to the downregulation of TLR9, allowing
HPV to effectively evade the innate immune response and delay the activation of adaptive
immunity.
Preventive HPV Vaccines
Immune Response in Natural HPV Infections
The most effective way to control viral infections is through preventive vaccination, and the
development of HPV vaccines is considered one of the scientific successes of the past two
decades. Natural genital infections lead to the production of serum neutralizing antibodies
against the L1 major capsid protein. However, this response is typically slow, with an average
time to produce antibodies after the first detection of HPV16 taking about 8 to 9 months.
Furthermore, only 50% to 70% of women with HPV infection experience seroconversion.
Nonetheless, anti-L1 antibodies generally persist in the body for at least 10 years, and low levels
of these antibodies can prevent disease.
In studies on animal models, neutralizing anti-L1 antibodies have been recognized as protective
against high-dose viral challenges, indicating that preventive HPV vaccines can be effective.
Because papillomaviruses do not grow well in tissue culture, the production of live attenuated or
killed vaccines was not feasible. However, technical advances in the early 1990s demonstrated
that if the L1 protein is expressed through eukaryotic expression systems, it can effectively
assemble into viral-like particles.
HPV L1 VLP Vaccine
There are two approved prophylactic HPV L1 VLP vaccines:
1. Cervarix®: A bivalent vaccine against HPV 16 and 18 produced by GlaxoSmithKline
Biologicals (GSK).
2. Gardasil®: A quadrivalent vaccine against HPV 16, 18, 6, and 11 produced by MSD
Merck.
Both vaccines have demonstrated their efficacy against HPV 16 and 18 related to high-grade
cervical intraepithelial lesions (CIN2/3) in women aged 15 to 26 years in randomized trials. The
immunization schedule consists of 3 vaccine doses (0, 1 or 2, and 6 months).
Further trials have shown that the quadrivalent vaccine is over 90% effective against HPV 6, 11,
16, and 18 related to external genital warts in heterosexual men and over 73% effective against
anal intraepithelial neoplasia in homosexual men.
Conclusion
Overall, HPV infection poses a significant public health challenge, and L1 VLP vaccines are
recognized as an effective means of preventing complications arising from this virus, particularly
related cancers. The development and utilization of these vaccines could reduce the disease
burden associated with HPV and save millions of lives.
Mechanisms of Protection Induced by Human Papillomavirus (HPV) Vaccines and Immune
Responses to HPV Infections
The mechanisms of protection conferred by HPV vaccines and the immune responses to natural
HPV infections constitute a complex and multifaceted area of study. Below, we explore the
protective mechanisms of vaccines and their differences from immune responses in natural
infections.
1. Protective Mechanisms Induced by Vaccines
The protective mechanisms of vaccines primarily operate through humoral immune responses
and the production of neutralizing antibodies. These antibodies can target the virus before it
enters epithelial cells and prevent infection. Specifically:
Neutralizing Antibodies: These antibodies can bind to L1 capsid proteins, preventing the virus
from entering host cells. In HPV vaccination, high levels of these antibodies lead to protection
against specific HPV types.
Humoral Immune Responses: Vaccination results in elevated antibody titers, which contribute to
the establishment of robust immune memory. These antibodies are typically polyclonal and
consist of various types that bind to different epitopes on the surface of viral-like particles
(VLPs).
2. Immune Responses in Natural Infections
In natural HPV infections, most infections are transient and typically resolve within 1 to 2 years
in 70% to 90% of cases. This highlights the crucial role of the host immune system in preventing
and controlling HPV infections. The immune responses in this context include:
Humoral Immune Response: Neutralizing antibodies are also produced in natural infections;
however, the levels of these antibodies are generally not as high as those induced by vaccines,
which may not be sufficient to protect against new infections.
Cellular Immune Response: Local and cellular immune responses, particularly against non-
structural viral proteins (such as E2 and E6), play a key role in recovery from infection. These
immune responses typically involve cytotoxic T cells and other activated immune cells.
3. Therapeutic Vaccines
While preventive vaccines have been significantly effective in reducing HPV infections and
associated diseases, therapeutic vaccines have yet to meet expectations.
Challenges of Therapeutic Vaccines: These vaccines must be capable of inducing effective local
and cellular immune responses that result in the regression of HPV-associated lesions. However,
current therapeutic vaccines have shown disappointing results, indicating a need for further
research in this area.
4. Conclusion
In conclusion, the protective mechanisms conferred by HPV vaccines are primarily based on
neutralizing antibodies and humoral immune responses. In contrast, natural infections necessitate
more complex immune responses that include both humoral and cellular mechanisms. Given the
challenges in developing therapeutic vaccines, further research is essential to better understand
these responses and improve vaccine efficacy.
The Role of HPV Viral Oncogenes E5, E6, and E7 in Chronic Inflammation and Cervical Cancer
The viral oncogenes E5, E6, and E7 from human papillomavirus (HPV) play a crucial role in the
development of chronic inflammation and cervical cancer. These oncogenes lead to an increased
expression of cyclooxygenase-2 (COX-2), resulting in elevated production of prostaglandins.
Prostaglandins significantly contribute to stimulating cell proliferation, angiogenesis, and
inhibiting apoptosis, which are key mechanisms of carcinogenesis.
Inflammatory cells recruited to the infection site can produce reactive oxygen species (ROS),
leading to DNA damage and creating a favorable environment for the malignant transformation
of cells. Multiple studies, including research by Kulkarni et al., have demonstrated increased
COX-2 expression in samples from patients with cervical intraepithelial neoplasia (CIN) or
neoplastic lesions of the cervix. HPV oncogenes also play a role in activating AP-1, a
transcription factor involved in COX-2 production.
The action of the E6 and E7 oncogenes on the NF-kB signaling pathway is also significant. The
suppression of NF-kB helps HPV evade immune surveillance. Similarly, a study by Castle et al.
showed the relationship between cervical inflammation and the presence of high-grade cervical
lesions, emphasizing inflammation as a risk factor for the progression to HPV-related cancer.
The Role of 8-Nitroguanine and Nitric Oxide
Research has indicated that 8-nitroguanine, a byproduct of inflammation, may play a role in
carcinogenesis. Immunohistochemical studies have examined the presence of 8-nitroguanine, 8-
oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG), and p16 in various samples, revealing that the
expression of 8-nitroguanine is higher in CIN samples than in condylomata acuminata and
positively correlates with CIN grade. On the other hand, nitric oxide (NO) is considered a marker
of inflammation, produced under inflammatory conditions, and can lead to DNA changes and
reductions in p53 and pRb influenced by E6 and E7 oncogenes.
The Role of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
Research indicates that non-steroidal anti-inflammatory drugs (NSAIDs), particularly those that
inhibit COX-2, can reduce tumor growth. One study suggested that frequent use of aspirin may
lower the risk of cervical cancer, although some other studies did not observe this association.
Celecoxib, a COX-2 inhibitor, has been shown to be effective in the prevention and treatment of
cervical cancer.
Recent studies have demonstrated that NSAIDs may induce apoptosis and effectively reduce cell
growth. Research indicates that ibuprofen and celecoxib can help reduce cell growth and induce
apoptosis, presenting themselves as potential treatments for cervical cancer.
However, recent reviews have shown that there is still insufficient evidence to support the
widespread use of NSAIDs for the prevention or treatment of CIN. Therefore, further research in
this area is necessary
