Efforts to explain spontaneous regression of cancer

A case of resected primary pulmonary pleomorphic carcinoma with long-term survival after multidisciplinary treatment

Background

Generally, primary pulmonary pleomorphic carcinoma is resistant to treatment and has a poor prognosis. We report a case of resected primary pulmonary pleomorphic carcinoma with long-term survival after multidisciplinary treatment.

Case presentation

A 74-year-old man with a history of emphysema, pneumoconiosis, and chronic bronchitis presented with left lung nodule and left adrenal tumor based on computed tomography. We suspected clinical T1bN0M1b, stage IVB lung cancer. Adrenalectomy of the left adrenal tumor yielded a definitive diagnosis of pleomorphic carcinoma. Chemotherapy was performed despite the spontaneous regression of lung lesions. Since lung lesions re-enlarged 11 months after adrenalectomy, the left lower lobe was partially resected followed by chemotherapy. The lung lesion was the primary lesion of the adrenal tumor. There was no recurrence 100 months after the lung resection.

Conclusions

The patient experienced long-term survival after multidisciplinary treatment. Both multidisciplinary treatment and immunological mechanisms caused spontaneous regression of the primary lesion.

Spontaneous Regression of Non-small Cell Lung Cancer: A Case Report and Literature Review

Spontaneous cancer regression is rare, and particularly rare for non-small cell lung cancer (NSCLC). The pathogenesis of spontaneous regressions is poorly understood, but of interest to many patients and providers. The infrequency of spontaneous regression makes it a challenging phenomenon to understand and study. We present a case of biopsy-proven NSCLC in a 73-year-old man that regressed without treatment.

Spontaneous remission of advanced progressive poorly differentiated non-small cell lung cancer: a case report and review of literature

BACKGROUND

Spontaneous remission (SR) of cancer is a very rare phenomenon of unknown mechanism. In particular, SR of non-small cell lung cancer (NSCLC) has been scarcely reported. We present the case of a 74-year-old woman with advanced, poorly differentiated NSCLC (highly expressing programmed death ligand-1 [PD-L1]) that progressed despite multiple lines of chemotherapy but then spontaneously remitted.

CASE PRESENTATION

The patient presented with hemoptysis and was diagnosed with stage IIIA poorly differentiated NSCLC via bronchoscopic biopsy. She had an unremarkable medical history and moderate performance status. The initial treatment plan was surgery after neoadjuvant chemotherapy. Despite conventional chemotherapy, follow-up chest computed tomography (CT) showed gradual tumor progression and she decided against further treatment after fifth-line chemotherapy. However, the size of lung mass was markedly decreased on follow-up chest CT one year after ceasing chemotherapy. Also, follow-up positron emission tomography images showed decreased metabolic activity in the lung mass and a percutaneous biopsy specimen from the diminished lung mass revealed no viable tumor cells. A diagnosis of SR of NSCLC was confirmed, and the patient was without tumor progression on follow-up nine months later. Later, PD-L1 immunostaining revealed high positivity (> 99%) in initial tumor cells.

CONCLUSION

Our case showing SR of poorly advanced NSCLC refractory to multiple lines of chemotherapy suggested the association between immunity and tumor regression.

Abscopal effect of high-dose-rate brachytherapy on pelvic bone metastases from renal cell carcinoma: a case report

Radiation therapy is considered an optimal partner for immunotherapies. Several pre-clinical studies have demonstrated that regression of distant metastases, at remote non-irradiated sites of the body, termed the “abscopal effect”, can be achieved by an appropriate timing and combination of radiation with immunotherapy. However, nearly all pre-clinical and clinical studies evaluating a combination of radiation and immunotherapies have used external beam radiation therapy. We present in this case report, the abscopal effect observed in a 30-year-old Japanese woman with metastatic renal cell carcinoma after the treatment with high-dose-rate interstitial brachytherapy combined with nivolumab. This is the first published report demonstrating an abscopal effect following brachytherapy for human malignancy. Our case indicates that immuno-oncology effects are not limited to external beam irradiation regimens as they can also be attained by brachytherapy.

Spontaneous regression of occult breast cancer with axillary lymph node metastasis: A case report

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This case showed spontaneous regression of both the primary and metastasis lesions.

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Histopathological findings suggested spontaneous regression of the tumor.

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The presence of CD8-positive lymphocytes suggests involvement of the immune response.

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Poor prognostic factors of malignant tumors might induce spontaneous regression.

Introduction

Spontaneous regression of a malignant tumor is defined as “the partial or complete disappearance of a malignant tumor in the absence of any treatment.” Herein, we report a case of occult breast cancer with axillary lymph node metastasis that showed spontaneous tumor regression based on the histopathological findings.

Presentation of the case

A 67-year-old woman presented with left armpit pain and a lump. Previous examination by another doctor revealed swelling of the left axillary lymph node, but it was difficult to identify the primary lesion. Needle biopsy of the left axillary lymph node revealed malignant tumor tissue with extensive necrosis on histological examination. On initial examination at our hospital, the left axillary lymph node was observed to have shrunk compared to previous observations. Moreover, findings indicated a suspected concentrated cyst in the left breast, with slight contrast enhancement on magnetic resonance imaging. Considering a diagnosis of occult breast cancer with axillary lymph node metastasis, excisional biopsy was performed for the left breast mass and axillary lymph node dissection for left axillary lymph node metastasis. Histological examination revealed a micro adenocarcinoma with lymphocyte infiltration in the left breast, and the viable tumor in the left axillary lymph node had disappeared. The histopathological findings of the primary tumor and dissected lymph nodes suggested the possibility of spontaneous regression of both the primary and metastatic lesions, because effective preoperative therapy was not performed.

A Case of Spontaneous Regression of Pulmonary Small Cell Carcinoma

An 82-year-old man was examined using chest computed tomography after treatment for pneumonia. Imaging showed a nodular shadow in the left lower lobe with associated enlarged lymph nodes. A polypoid tumour was observed on bronchoscopic examination, and the histological findings showed pulmonary small cell carcinoma with infiltration of CD3-positive and CD8-positive lymphocytes. The patient declined any antitumoural therapy and experienced an exacerbation of heart failure treated with atrial natriuretic peptide. Eighteen months after the diagnosis, the polypoid tumour had disappeared. T lymphocyte-mediated immunity and the antitumoural effects of atrial natriuretic peptide may have influenced the observed spontaneous regression.

Spontaneous Regression of Recurrent Undifferentiated Carcinoma of the Endometrium

We herein report a very rare case of spontaneous regression of recurrent undifferentiated carcinoma of the endometrium. An 80-year-old woman had undergone total hysterectomy with bilateral adnexectomy for undifferentiated carcinoma of the endometrium. The cancer recurred locally 10 months after surgery and then metastasized to the lung and liver. After she and her family elected to receive supportive care without active treatment, the local recurrences dramatically decreased, and the metastases of the lung, liver, and peritoneum also disappeared. This case showed that spontaneous regression can occur even with malignant tumors showing an extremely poor prognosis, such as undifferentiated carcinoma of the endometrium.

Spontaneous Regression of Myxofibrosarcoma of the Thigh after Open Biopsy

Spontaneous regression of sarcoma is exceedingly rare. A 62-year-old male presented with myxofibrosarcoma of the thigh which regressed after open biopsy. Treatment strategy for this condition is not well-documented in the literature. In this report, we describe the case of a spontaneously regressed myxofibrosarcoma successfully treated by resection where the extent of the tumor was determined from the initial MRI. This case demonstrates that myxofibrosarcoma has the potential to regress spontaneously, and astute awareness of this phenomenon is necessary for appropriate management of this condition.

Spontaneous Regression of Primary Pulmonary Synovial Sarcoma

We report a rare case of primary pulmonary synovial sarcoma that underwent spontaneous regression after a transbronchial biopsy. A 38-year-old woman with a well-demarcated solitary mass shadow on chest roentgenogram was referred to us. A transbronchial biopsy was performed, and immunohistochemical results as well as detection of SYT-SSX1 (SYnovial sarcoma Translocation-Synovial Sarcoma X chromosome breakpoint) transcripts resulted in a diagnosis of synovial sarcoma. A right lower lobectomy was performed during video-assisted thoracoscopic surgery. Pathologic examination revealed widespread coagulative necrosis with feeding arterioles occluded by organized thrombi. To our knowledge, this is the first report of a case of spontaneous regression of primary pulmonary synovial sarcoma.

Spontaneous regression of hepatocellular carcinoma with reduction in angiogenesis-related cytokines after treatment with sodium-glucose cotransporter 2 inhibitor in a cirrhotic patient with diabetes mellitus

Spontaneous regression of hepatocellular carcinoma (HCC) is a rare event, and the pathogenesis remains unclear. Here, we present a case of spontaneous regression of HCC after treatment with sodium-glucose cotransporter 2 inhibitor (SGLT2i) in a cirrhotic patient with diabetes mellitus (DM). A 68-year-old man regularly visited our hospital for follow-up of HCC after treatment with transcatheter arterial chemoembolization, and management of liver cirrhosis and type 2 DM. Contrast-enhanced computed tomography scan showed a hypervascular tumor in the liver and elevated serum α-fetoprotein levels, indicating the recurrence of HCC. Simultaneously, the hemoglobin A1c value increased to 8.0%; therefore, he was treated with SGLT2i (canagliflozin 100 mg/day). Ten weeks after the initiation of SGLT2i treatment, he was admitted to our hospital for treatment of recurrent HCC. However, the hypervascular tumor had disappeared, and the elevated serum α-fetoprotein level had decreased to normal limits, indicating spontaneous regression of HCC. In addition, an angiogenesis array analysis revealed downregulated protein expression of matrix metalloproteinase-8, angiopoietin-1/2, platelet-derived growth factor-AA, and prolactin at 10 weeks after SGLT2i treatment. In this report, we first describe a case of spontaneous regression of HCC with reduction in angiogenesis-related cytokines after SGLT2i treatment.

Spontaneous Regression of Hepatocellular Carcinoma and Review of Reports in the Published English Literature

Background

Spontaneous regression of hepatocellular carcinoma (HCC) is a rare event, although it has been described by numerous groups. The long-term fate of individuals experiencing an SR is not well described, and the underlying mechanism(s) of SR are unknown. Case Presentation: A 79-year-old Asian female with metastatic HCC taking only valsartan for hypertension had a marked reduction in tumor dimension in the primary tumor and the pulmonary metastases. Serum alpha-fetoprotein (AFP) decreased from 17,833 μg/L to 26 μg/L. Her disease progressed after 71 months, and she died shortly after. In a review of 66 patients with SR reported in the English literature, median survival was 83 months. Median survival in 37 cases that underwent resection after SR was 108 months.

Conclusions

The case and a review of the literature illustrate that SR is often durable and associated with an excellent prognosis. Understanding the underlying mechanism of SR may point to novel therapeutic strategies.

Spontaneous regression of a carcinoid tumor that required resection owing to its reappearance and subsequent enlargement after 2 years: a case report

We present a rare case of spontaneous regression in a typical lung carcinoid. A 20-year-old woman with an abnormal shadow on a chest radiograph was admitted to our hospital. Computed tomography revealed a smooth nodule in the left S1 + 2 segment. At the 6-month follow-up, the nodule had regressed without treatment. At the 2-year follow-up, the tumor reappeared in the same place as before. We performed left upper lobectomy via 4-port thoracoscopic surgery. A pathological examination revealed a typical carcinoid. Lung carcinoids can spontaneously regress; long-term follow-up is important for timely detection of tumor reappearance.

Spontaneous Regression of Germinomas After Salvage Surgery and Possible Mechanism of Induced Apoptosis

BACKGROUND

A few cases of spontaneous regression of germ cell tumors have been reported. Possible mechanisms include steroid medication, surgical intervention, diagnostic radiation exposure, and immune response. None of these hypotheses has been supported by sufficient data.

CASE DESCRIPTION

Two cases of germinoma demonstrated spontaneous regression before antitumor therapy. In the first case, a 19-year-old man presented with acute hydrocephalus due to a pineal mass and underwent emergent endoscopic third ventriculostomy. The pineal tumor started to regress on the 4th postoperative day after endoscopic third ventriculostomy. In the second case, a 22-year-old man presented with acute hydrocephalus and panhypopituitarism due to a suprasellar mass and underwent emergent external ventricular drainage, biopsy, and septostomy on the day of admission. Apparent regression of the tumor was discovered on the 5th day after initial surgery. Pathologic diagnosis was pure germinoma in both cases. Remarkable accumulations of CD4-positive lymphocytes and some apoptotic cells positive for terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling staining were detected in both cases. Diagnostic radiation exposure is the only common condition in all reported cases.

CONCLUSIONS

This unusual phenomenon of spontaneous regression of germinoma may be caused by a combination of pathognomonic characteristics of anatomic location with paraventricular development and stress induction as a trigger, such as salvage surgery or diagnostic radiation, including at extremely low dosage.

Spontaneous regression of lung squamous cell carcinoma with synchronous mediastinal progression: A case report

Spontaneous regression (SR) of cancer implies the partial or complete disappearance of malignant disease without or with adequate medical treatment. Typically, SR of cancer is a sporadic event, especially in non‐small cell lung cancer (NSCLC). Although the underlying mechanism of SR remains unknown, stimulation of an immunological response has been proposed. Herein, we report the case of a 56‐year‐old woman exhibiting SR of NSCLC with a mediastinal disease. Despite regression of the primary site after a lung biopsy, simultaneous progression of mediastinal lymph node metastasis occurred. Specimens obtained by surgical resection pathologically confirmed both primary and metastatic sites. Reportedly, primary and metastatic tumors shrink synchronously in SR of metastatic NSCLCs. Thus, the fact that the SR of NSCLC can present inconsistent development in primary and metastatic sites should be considered, and direct intervention is recommended if physicians diagnose this phenomenon.

Spontaneous Regression of Hepatocellular Carcinoma with Portal Vein Tumor Thrombus

An 83-year-old man underwent transcatheter arterial chemoembolization (TACE) for a 20-mm hepatocellular carcinoma (HCC) in Couinaud's segment 4. Computed tomography (CT) 4 months after TACE showed tumor thrombus in the portal vein in addition to diffuse metastases and arterioportal shunts in the left lobe. Although we performed the best supportive care, the tumor thrombus in the portal vein and tumors in the left lobe had completely disappeared on CT 16 months after the TACE. Rapidly grown portal vein tumor thrombus and arterioportal shunt might be the causes of spontaneous regression of HCC, probably associated with tumor hypoxia.

Spontaneous regression of locally advanced nonsmall cell lung cancer: A case report

RATIONALE

Spontaneous regression of non-small cell lung cancer is exceptionally rare.

PATIENT CONCERNS

Treatment-related toxicity.

DIAGNOSES

We report a case of a patient diagnosed with locally advanced non-small cell lung cancer.

INTERVENTIONS

The patient declined potentially curative treatment, and did not receive any anti-cancer treatment.

OUTCOMES

He has survived more than two years since his initial diagnosis, maintaining his good performance status. Serial imaging with computed tomography scans showed tumour regression and near-complete resolution of his disease.

LESSONS

Spontaneous regression of non-small cell lung cancer, by virtue of its scarcity, has not been well-studied and is poorly understood. Further studies are required, in order to clarify the mechanisms by which spontaneous regression occurs, and possibly identify new targets for cancer treatment.

Case Series: Abscopal Benefit of Surgery in 3 Immunotherapy-Treated Patients With Unresectable Cancer

For all of the optimism that immunotherapy has engendered, the flip side is that 7/10 patients with susceptible tumor types do not respond, while in nonsusceptible tumor types the response rates are significantly lower. In contradiction of the current orthodoxy against surgery in the setting of unresectable disease, we present 3 examples of immunotherapy-treated patients with widespread recurrence who experienced dramatic clinical improvement following debulking/metastasectomy. Taken together with examples from the literature that correlate longer survival with surgical intervention during treatment with immunotherapy, these 3 cases suggest that a new paradigm involving a wider role for surgery in the management of these patients should be explored. Possible mechanisms by which surgery may synergize with immunotherapy and improve outcomes are also discussed.

Spontaneous regression of metastatic squamous cell lung cancer

Spontaneous regression (SR) of cancer is a rare but confirmed spectacular phenomenon, and it is even rarer in the context of advanced NSCLC. It is essential to understand this phenomenon in order to elucidate the nature of neoplastic disease and develop new treatment methods.

William Bradley Coley, MD, and the phenomenon of spontaneous regression

The standard definition of spontaneous regression (SR) of cancer is as follows, "…when a malignant tumor partially or completely disappears without treatment or in the presence of therapy which is considered inadequate to exert a significant influence on neoplastic disease." SR is also known as Saint Peregrine tumor, the name taken from a young priest, Peregrine Laziosi (1260 [5]-1345, exact date is unknown), who had been diagnosed with a tumor of the tibia. The mass eventually grew so large that it broke through the skin and became severely infected. The available treatment for this condition was limited to amputation. Historical records report that on the day of surgery, physicians found that the tumor had disappeared and reportedly never returned. To date, the medical literature consists only of individual case studies and overviews of this phenomenon. The most cited work on the subject was done by surgeons Tilden Everson and Warren Cole who reviewed 176 published cases of SR from 1900 to 1960. While a percentage of these were found not to be cases of SR, there remained a number of unexplained cases. A frequent theme in many cases of SR is the co-occurrence of infection. Given the current interest in immunotherapy in the treatment of cancer, this article discusses one of the very early pioneers of this theory, William Bradley Coley, MD, a surgeon who was clearly ahead of his time. Ostracized by colleagues for his belief that stimulation of the immune system could in fact produce a regression of cancer, Coley remained convinced that his theory was right and, while he was not familiar with cytokines such as tumor necrosis factor (TNF), interferons, and streptokinase, he knew instinctively that an innate immune response was taking place.

Spontaneous regression of colorectal liver metastasis

A 72-year-old woman with advanced ascending colon cancer and an intraductal papillary mucinous neoplasm (IPMN) of the pancreatic head was treated by right hemicolectomy (RHC) and pylorus-preserving pancreaticoduodenectomy (PpPD). Adjuvant chemotherapy was not administered. Multimodal examinations at 5 months after surgery detected a solitary metastatic liver tumor derived from cancer of the ascending colon. Liver resection proceeded at 7 months after the first surgery. A pathological study of a surgical specimen of the liver identified a necrotic nodule that did not contain viable tumor cells. However, an immunohistological study of the hepatic mass indicated metastasis derived from cancer of the ascending colon. These findings were consistent with total necrosis of a liver metastasis of colorectal cancer. The mechanism of spontaneous regression of tumors remains unexplained. In our case, pancreaticoduodenectomy was performed at the same time as right hemicolectomy, which involved a risk of continuous biliary infection after biliary tract reconstruction. A host immune response to chronic biliary tract infection might have been involved in the spontaneous regression of liver metastasis. Spontaneous regression of colorectal liver metastasis is rare, and the mechanism remains unknown. This needs to be investigated in more tissues from patients who have experienced this phenomenon.

Spontaneous regression of a primary squamous cell lung cancer following biopsy: a case report

Background

Spontaneous regression has been defined as occurring when the malignant tumor mass partially or completely disappears without any treatment or as a result of a therapy considered inadequate to influence systemic neoplastic disease. Recently, studies have implicated immunological responses as likely being involved. We report a case of a patient with squamous cell carcinoma of the lung who experienced spontaneous regression following biopsy without other intervention.

Case presentation

A 57-year-old white man was referred to our pulmonary clinic after an incidental finding of a nodule in the lower lobe of his left lung. Thoracic computed tomography revealed a 2.0 × 1.4 × 1.5 cm spiculated nodule in the superior segment of the left lower lobe. Workup identified the mass as a squamous cell carcinoma that was clinically staged as T1M0N0. The patient deferred treatment of this lesion. He undertook no significant lifestyle or medical changes. Three months later, computed tomography revealed that, compared with the initial study, the solitary mass had decreased in size to 1.6 × 0.9 × 0.9 cm. Follow-up computed tomography 1 year after the original workup demonstrated that the nodule had stabilized to its smaller size.

Conclusions

Studies have shown that immunological response can be initiated by trauma to an area. Because the tumor regression became evident in our patient only after the tissue biopsy, his immune response to the surgical procedure seems to be a plausible contributor to the spontaneous regression. Further understanding of spontaneous regression can potentially impact the identification of neoplastic drug targets or even the course of a patient’s treatment plan and goals.

Lymph Node Metastases of Merkel Cell Carcinoma from Unknown Primary Site: Report of Three Cases

Merkel cell carcinoma (MCC) is an uncommon aggressive neuroendocrine skin carcinoma. It usually affects sun-exposed skin of white elderly people. MCC is characterized by a high incidence of early locoregional relapse and distant metastases. Because of its rarity and the resulting lack of prospective randomized trials, data regarding the optimal treatment of MCC are limited. Despite aggressive multimodality treatment, the prognosis of patients bearing MCC is often poor. We report three cases of lymph node metastases of MCC with unknown primary sites. Two patients died 17 and 28 months after diagnosis due to brain and pancreatic metastases, respectively, without evidence of cutaneous disease. The third patient is alive and free of tumor at 16 months from the diagnosis. After an accurate diagnosis of lymph node metastases from MCC, the absence of a primary tumor at complete initial evaluation and during adequate follow-up can confirm this particular clinical scenario. The prognosis seems to be analogous to that of cases with similar disease stage (lymph node involvement) but a known primary site.

Spontaneous regression of a pulmonary adenocarcinoma after core needle biopsy

Spontaneous regression (SR) of cancer, especially lung cancer, is a rare biological event with a mechanism that is not currently understood. Immunological mechanisms seem to be the stronger explanation in SR of a lung cancer. We report the rare case of SR of a lung adenocarcinoma stage IA, in a 75-year-old man, which was incidentally diagnosed and histologically confirmed. Due to the patient’s comorbidities and his poor pulmonary function, stereotactic radiotherapy was scheduled. However, by the time the treatment was due to start, the tumor was no longer detectable.

Spontaneous regression of anterior mediastinal seminoma with normalization of β-human chorionic gonadotropin levels

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Spontaneous regression of anterior mediastinal seminoma with normalization of β-human chorionic gonadotropin (β-hCG) levels shows good clinical outcome and sensitive to chemotherapy.

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Video-assisted thoracic surgery (VATS) is effective solution for definite diagnosis of anterior mediastinal.

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Apoptosis may be a reason of tumors’ spontaneous regression.

Introduction

Although spontaneous regression (SR) of anterior mediastinal seminoma is very rare with normalization of β-human chorionic gonadotropin (β-hCG) level, video-assisted thoracic surgery (VATS) is the most effective solution for definite diagnosis of indeterminate anterior mediastinal masses.

Diagnosis, therapeutic interventions, and outcomes

A rare case of an asymptomatic 37-year-old man with an anterior mediastinal mass that was detected on a routine chest X-ray is presented. Computed tomography (CT) showed a large anterior mediastinal tumor with superior vena cava invasion and SR before VATS for definitive diagnosis. On pathology, the definitive diagnosis was seminoma. Microscopic examination showed abundant apoptotic cells within the tumor. Chemotherapy (bleomycin 30 mg/day, etoposide 200 mg/day, cisplatin 40 mg/day) was given to this patient, and the tumor showed high sensitivity.

Conclusion

Anterior mediastinal seminoma showing SR induced by spontaneous apoptosis of tumor cells may have good sensitivity to chemotherapy, and a good clinical outcome may be achieved in these patients. This case also highlights that VATS is the most effective solution for definite diagnosis of indeterminate anterior mediastinal masses.

Regression of Pineal Lesions: Spontaneous or Iatrogenic? A Case Report and Systematic Literature Review

BACKGROUND

Tumors arising from the pineal region account for approximately 1% of intracranial neoplasms. We present a case of a previously healthy 5-year-old boy with an acute onset of headache. A magnetic resonance imaging (MRI) scan showed a pineal mass with aqueduct compression. The patient was scheduled for tumor resection. An endoscopic third ventriculostomy was performed in advance for the treatment of hydrocephalus. Afterwards, MRI showed a relevant regression of the pineal mass without specific treatment. Consequently, surgery was cancelled and further MRI follow-up showed a regression of the mass and a constant tumor mass over a period of 30 months. Spontaneous regression of malignant tumors is a rare phenomenon with an incidence of 1 of 60,000-100,000 cases. Only a few cases with spontaneous regression of pineal tumors have been reported.

METHODS

We performed a systematic literature review according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines on spontaneously regressing pineal lesions and found 13 cases in the literature.

RESULTS

Six hypotheses for explaining tumor regression were found, comprising treatment with steroids, effects of diagnostic irradiation, treatment of hydrocephalus, pineal apoplexy, surgical trauma, and immunologic mechanisms. None of these mechanisms was evidentiary. However, in all reported cases, some kind of treatment (e.g. treatment of hydrocephalus, application of steroids, and so on) has been performed before tumor regression.

CONCLUSIONS

The clinician has to bear in mind that regression of pineal tumors might be triggered by use of steroids, for example, and in cases of improvement of the patient's presenting symptoms, new MRI scans should be performed.

Spontaneous regression of gestational trophoblastic neoplasia

•We present two cases of postmolar gestational trophoblastic neoplasia (GTN).•Both cases presented with lung metastases after hydatidiform mole.•Both cases showed spontaneous regression without treatment.•The mechanism behind this phenomenon remains unclear.•Patients with postmolar GTN and declining hCG values may not need chemotherapy.

Tumor reductive therapies and antitumor immunity

Tumor reductive therapy is to reduce tumor burden through direct killing of tumor cells. So far, there is no report on the connection between antitumor immunity and tumor reductive therapies. In the last few years, a new category of cancer treatment, immunotherapy, emerged and they are categorized separately from classic cytotoxic treatments (chemo and radiation therapy). The most prominent examples include cellular therapies (LAK and CAR-T) and immune checkpoint inhibitors (anti-PD-1 and CTLA-4). Recent advances in clinical immunotherapy and our understanding of the mechanism behind them revealed that these therapies have a closer relationship with classic cancer treatments than we thought. In many cases, the effectiveness of classic therapies is heavily influenced by the status of the underlying antitumor-immunity. On the other hand, immunotherapies have shown better outcome when combined with tumor reductive therapies, not only due to the combined effects of tumor killing by each therapy but also because of a synergy between the two. Many clinical observations can be explained once we start to look at these classic therapies from an immunity standpoint. We have seen their direct effect on tumor antigen in vivo that they impact antitumor immunity more than we have realized. In turn, antitumor immunity contributes to tumor control and destruction as well. This review will take the immunological view of the classic therapies and summarize historical as well as recent findings in animal and clinical studies to make the argument that most of the cancer treatments exert their ultimate efficacy through antitumor immunity.

Spontaneous Regression of Endobronchial Carcinoid Tumor

Spontaneous regression (SR) of cancer refers to partial or complete disappearance of a malignant tumor in the absence of treatment or in the presence of therapy, which is considered inadequate to exert a significant influence on the growth of neoplastic disease. SR is a very rare phenomenon in primary lung cancers. Follow-up of these patients is generally either by imaging or bronchoscopy. We present a patient with SR of an endobronchial carcinoid, followed by serial bronchoscopies and biopsy over a 24-month period.

Spontaneous regression of transverse colon cancer: a case report

Spontaneous regression (SR) of many malignant tumors has been well documented, with an approximate incidence of one per 60,000–100,000 cancer patients. However, SR of colorectal cancer (CRC) is very rare, accounting for less than 2% of such cases. We report a case of SR of transverse colon cancer in an 80-year-old man undergoing outpatient follow-up after surgical treatment of early gastric cancer. Colonoscopy (CS) revealed a Borrmann type II tumor in the transverse colon measuring 30 × 30 mm. Because the patient underwent anticoagulant therapy, we did not perform a biopsy at that time. A second CS was performed 1 week after the initial examination and revealed tumor shrinkage to a diameter of 20 mm and a shift to the Borrmann type III morphology. Biopsy revealed a poorly differentiated adenocarcinoma. One week after the second CS, we performed a partial resection of the transverse colon and D2 lymph node dissection. Histopathology revealed inflammatory cell infiltration and fibrosis from the submucosal to muscularis propria layers in the absence of cancer cells, leading to pathological staging of pStage 0 (T0N0). The patient had an uneventful recovery, and CS performed at 5 months postoperatively revealed the absence of a tumor in the colon and rectum. The patient continues to be followed up as an outpatient at 12 months postoperatively, and no recurrence has been observed.

Spontaneous Regression of Intravascular Large B-Cell Lymphoma and Apoptosis of Lymphoma Cells: A Case Report

A 61-year-old Japanese woman presented with hemophagocytic syndrome (HPS) and suffered from intravascular large B-cell lymphoma (IVLBCL). After a few days of supportive care, her condition improved without any anti-cancer drugs or steroids. She experienced recurrences of HPS at 15 mon and 21 mon after first presentation, but lymphoma cells were not observed. Relapse of IVLBCL with pulmonary involvement occurred 27 mon after first presentation. She underwent R-CHOP therapy followed by autologous stem cell transplantation. She is currently alive and without lymphoma. Immunostaining by anti-ssDNA suggested that spontaneous regression may have been due to apoptosis of the lymphoma cells.

Spontaneous Regression of Hepatocellular Carcinoma with Multiple Lung Metastases: A Case Report and Review of the Literature

Spontaneous regression of hepatocellular carcinoma (HCC) is a rare event. Here we present a case of spontaneous regression of metastatic HCC. A 53-year-old man with hepatitis C and alcoholic cirrhosis was found to have a large liver mass consistent with HCC based on its radiographic features. Imaging also revealed left portal and hepatic vein thrombosis, as well as multiple lung nodules concerning for metastases. Approximately 2 months after the initial diagnosis, both the primary liver lesion and the lung metastases decreased in size and eventually resolved without any intervention. Thereafter, the left hepatic vein thrombus progressed into the inferior vena cava and the right atrium, and the patient died due to right heart failure. In this case report and literature review, we discuss the potential mechanisms for and review the literature on spontaneous regression of metastatic HCC.

Vanished: Is This for Real?

Spontaneous regression (SR) of lung cancer is especially rare. We report a case of an early endobronchial squamous cell carcinoma that exhibited complete radiologic and pathologic SR soon after diagnosis. The patient was monitored radiologically and bronchoscopically at regular intervals and to date, the biopsy samples have been negative. Remarkably, SR has been maintained 6 years after diagnosis, without local recurrence or distant metastases. Many hypotheses abound to explain how complete SR was achieved and maintained despite the lack of treatment.

Resected Hepatocellular Carcinoma in a Patient with Crohn's Disease on Azathioprine

Hepatocellular carcinoma rarely occurs in patients without underlying cirrhosis or liver disease. While inflammatory bowel disease has been linked to certain forms of liver disease, hepatocellular carcinoma is exceedingly rare in these patients. We report the twelfth case of hepatocellular carcinoma in a patient with Crohn's disease. The patient is a 61-year-old with longstanding Crohn's disease who was treated with azathioprine and was found to have elevated liver enzymes and a new 3-cm liver mass on ultrasound. A complete workup for underlying liver disease was unremarkable and liver biopsy revealed hepatocellular carcinoma. The patient underwent a hepatic resection, and there is no evidence of recurrence at the 11-month follow-up. The resection specimen showed no evidence of cancer despite the initial biopsy revealing hepatocellular carcinoma. This case represents the third biopsy-proven complete spontaneous regression of hepatocellular carcinoma. Although large studies have failed to show a definite link between azathioprine and hepatocellular carcinoma, the relationship remains concerning given the multiple case reports suggesting a possible association. Clinicians should exercise a high degree of suspicion in patients with Crohn's disease who present with elevated liver enzymes, especially those on azathioprine therapy.

Spontaneous neoplastic remission of hepatocellular carcinoma

We report on a case of a 57-year-old male who underwent a curative resection for hepatocellular carcinoma (HCC) with histological confirmation of a spontaneously necrotized tumor. Initial serum AFP level was 4,778 ng/mL. A 3.7 cm hyperechoic mass in segment 6 of the liver was observed on ultrasonography and dynamic contrast-enhanced liver MRI showed a 3.7 × 3.1 cm sized HCC. He was scheduled to undergo curative surgical resection under the clinical diagnosis of an early stage HCC (Barcelona Clinic Liver Cancer stage A). Without treatment, the serum AFP level declined rapidly to 50 ng/mL over five weeks. He underwent curative wedge resection of segment 6 of the liver. Histology revealed complete necrosis of the mass rimmed by inflamed fibrous capsule on a background of HBV-related cirrhosis with infiltration of lymphoplasma cells. Exact pathophysiology underlying this event is unknown. Among the proposed mechanisms of spontaneous neoplastic remission of HCC, circulatory disturbance and activation of host immune response offer the most scientific explanation for the complete histologic necrosis of HCC in the resected mass seen in our patient.

Spontaneous regression in advanced squamous cell lung carcinoma

Spontaneous regression of malignant tumors is rare especially of lung tumor and biological mechanism of such remission has not been addressed. We report the case of a 79-year-old Korean patient with non-small cell lung cancer, squamous cell cancer with a right hilar tumor and multiple lymph nodes, lung to lung metastasis that spontaneously regressed without any therapies. He has sustained partial remission state for one year and eight months after the first histological diagnosis.

Primary Pulmonary Synovial Sarcoma Showing a Prolonged Survival with Multimodality Therapy

A 54-year-old man was referred to our hospital due to a mass shadow noted on a chest X-ray. Thoracoscopic lobectomy yielded a diagnosis of primary pulmonary synovial sarcoma according to the histology and SYT-SSX1 gene analyses. Five months after the thoracic surgery, he developed brain metastasis; therefore, we performed resection of the brain metastatic focus followed by radiotherapy. As a local recurrence in the thoracic cavity concurrently emerged, systemic chemotherapy was also administered. These observations indicated that a multidisciplinary approach may be useful against primary pulmonary synovial sarcoma, although there is presently no established therapeutic strategy due to its rarity and highly aggressive nature.

Pulmonary Mucosa-associated Lymphoid Tissue Lymphoma with Spontaneous Regression after Computed Tomography-guided Needle Biopsy: A Case Report and Summary of 8 Reported Cases

A 72-year-old woman was admitted to our hospital with a solitary right lung nodule. She had no symptoms and no abnormal physical findings except for bladder cancer. Tumor markers were mildly elevated but no other abnormal laboratory data were found. The nodule was diagnosed to be pulmonary mucosa-associated lymphoid tissue lymphoma on computed tomography-guided needle biopsy. Thereafter, she first underwent surgery for bladder cancer. The lung nodule was found to have slightly increased at three months and then disappeared at 15 months after the biopsy. The notable clinical course of this rare disease suggests the effectiveness of a non-interventional treatment strategy.

Spontaneous complete regression of hypothalamic pilocytic astrocytoma after partial resection in a child, complicated with Stevens-Johnson syndrome: a case report and literature review

Pilocytic astrocytoma (PA) is the most common pediatric central nervous system glial neoplasm and the most common pediatric cerebellar tumor. The spontaneous regression that occurs after partial/subtotal resection is multifactorial, depending on multiple factors, as for the case of humoral and cell-mediated immune responses of the host to the implanted tumor. A 7-year-old boy was referred to a neurosurgery clinic with headache. Further imaging workup revealed hypothalamic PA. Partial resection of the lesions was performed with right-side pterional approach. The patient developed a severe panmucositis [Stevens-Johnson syndrome (SJS)] and respiratory failure plus conjunctivitis, due to phenytoin allergy. During the patient's 6-month follow-up, postoperative magnetic resonance imaging (MRI) revealed a residual tumor, and about 9 months later (at 15 months postoperatively), the MRI showed total regression of the tumor. Clinically, symptomatic PA may undergo spontaneous regression after partial resection. We report a well-documented case of spontaneous regression hypothalamic PA after partial resection that complicated with SJS. Immune system reaction in SJS may have a role in tumor behavior and spontaneous regression. Multiple studies confirmed spontaneous regression in PA after partial/subtotal resection. This phenomenon occurs due to humoral and cell-mediated host immune responses to the implanted tumor. The immune system reaction in SJS may have a role in tumor behavior and spontaneous regression.

Thymoma exhibiting spontaneous regression in size, pleural effusion and serum cytokeratin fragment level: A case report

A 30-year-old man was admitted to Toho University Omori Medical Center for assessment of right chest pain and fever. Chest computed tomography (CT) revealed an anterior mediastinal tumor sized 11.0×6.0×5.0 cm, with right pleural effusion. The laboratory analysis revealed elevated white blood cell count (11,000/µl), C-reactive protein (4.1 mg/dl) and cytokeratin fragment (CYFRA; 12.7 ng/ml; normal, <2 ng/ml). The level of CYFRA in the pleural effusion was also markedly elevated (143 ng/ml). On the first day after admission (6 days after the initial CT), there was a mild regression on CT (10.0×5.5×4.4 cm; reduction rate, 26.7%), with decrease of the pleural effusion volume. A CT-guided needle biopsy was performed, but the findings were not conclusive, as most of the tissue was necrotic. Seven days later (13 days after the initial CT), a CT revealed further regression (9.5×5.4×4.2 cm; reduction rate, 34.7%) with disappearance of the pleural effusion. The patient was followed up on an outpatient basis. At 35 days after the initial CT, the tumor continued to shrink without treatment (8.0×3.6×3.0 cm; reduction rate, 73.8%) and the serum CYFRA level had decreased to 0.8 ng/ml, although it had not returned to normal levels. At 62 days after the initial CT, the patient underwent surgical resection. The resected specimen was diagnosed as thymoma (World Health Organization type B2; Masaoka classification, stage II), with prominent degeneration and necrosis. One possible cause of the spontaneous regression may be increased internal pressure, probably associated with rapid tumor growth, leading to massive necrosis with resulting chest pain, inflammatory reaction with pleural effusion and subsequent tumor regression. The serum CYFRA level may be a useful marker for the evaluation of the clinical course of thymoma with extensive necrosis.