JP2018072394A - Tumor model - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tumor model that has similar properties to those of an actual tumor and is useful for a surgical simulation and the like.SOLUTION: The present invention provides a tumor model in which a plurality of particles containing absorbent polymers are bound together with a binder containing water to form an assembly, and the assembly is surrounded by a rubber which is a water-insoluble film. The absorbent polymer has a structure derived from poly (meth) acrylic acid, and/or alkali metal salt of poly (meth) acrylic acid. The binder contains polyvinyl alcohol resin, borax and water.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tumor model.

Conventionally, various models have been proposed for practicing procedures such as surgery. For example, a hydrogel in which water is included in a three-dimensional network structure formed by combining a water-soluble organic polymer and a clay mineral has been proposed (for example, see Patent Document 1). It is disclosed that this is suitable as an organ model for procedure practice.
By the way, there are various types of tumors in the human body. For example, looking at hardness, some tumors are so soft that they can be scraped and removed, while others are as hard as cartilage. Thus, tumors are wide even if only focusing on the property of hardness.
Under such circumstances, various tumor models have been proposed for use in surgical removal surgery.

JP2015-138192A

  However, the conventionally proposed tumor model has characteristics different from that of an actual tumor, and thus further improvement has been demanded.

  The present invention has been made in view of the above-described conventional situation, and an object thereof is to provide a tumor model whose characteristics are similar to those of an actual tumor as compared with a conventional tumor model.

  The tumor model of the present invention is a tumor model in which a plurality of particles containing a water-absorbing polymer are combined by a water-containing binder to form an aggregate, and the aggregate is surrounded by a water-insoluble film. It is.

  The tumor model according to the present invention is similar in characteristics to an actual tumor. Therefore, it is useful for surgery simulation and the like.

It is a schematic diagram of the cross section of a tumor model. It is a schematic diagram which shows the manufacturing method of a tumor model. It is a schematic diagram which shows the manufacturing method of a tumor model. It is a schematic diagram which shows the manufacturing method of a tumor model. It is a photograph which shows the result of drying experiment. It is a table | surface which shows the result of the sensory test of the doctor A. It is a table | surface which shows the result of the sensory test of the doctor B. FIG. It is a table | surface which shows the result of the sensory test of the doctor C. FIG.

  A preferred embodiment of the present invention will be described.

  In the tumor model of the present invention, a structure derived from a water-soluble film is preferably present at the outer edge of the aggregate. In the process of creating a tumor model, an aggregate in which a plurality of particles containing a water-absorbing polymer are bound is difficult to handle as it is. When the aggregate is wrapped in a water-soluble film, the handling property of the aggregate is improved, and the production of a tumor model becomes easy. In addition, a water-soluble membrane is used in the process of preparing the tumor model, but in the completed tumor model, the shape of the membrane may be maintained, or the membrane may be dissolved or dispersed. It may be.

  In the tumor model of the present invention, the water-absorbing polymer preferably has a structure derived from poly (meth) acrylic acid and / or an alkali metal salt of poly (meth) acrylic acid. In this case, the following effects are obtained. That is, when it has a structure derived from poly (meth) acrylic acid and / or an alkali metal salt of poly (meth) acrylic acid, the water-absorbing polymer becomes transparent and forms a blood vessel model or the like in the tumor model. Even in this case, it is easy to see the blood vessel model. Therefore, it is extremely useful for surgery simulation and the like.

  In the tumor model of the present invention, the binder preferably contains a polyvinyl alcohol-based resin, borax, and water. In this case, the following effects are obtained. That is, when the binding material contains polyvinyl alcohol-based resin, borax, and water, the binding material becomes transparent, and even when a blood vessel model or the like is formed in the tumor model, the blood vessel model or the like is easy to see. Therefore, it is extremely useful for surgery simulation and the like.

The present invention will be described in detail below.
In the tumor model of the present invention, a plurality of particles containing a water-absorbing polymer are combined by a water-containing binder to form an aggregate, and the aggregate is surrounded by a water-insoluble film. In FIG. 1, the example is shown with the schematic diagram. Reference numeral 1 represents a tumor model, reference numeral 3 represents a particle containing a water-absorbing polymer, reference numeral 5 represents a binder containing water, reference numeral 7 represents an aggregate, and reference numeral 9 represents a water-insoluble membrane. Show. Reference numeral 11 denotes a structure derived from a water-soluble film.

(Water-absorbing polymer)
The water-absorbing polymer is not particularly limited as long as it is a polymer having water absorption, and a wide range of polymers can be used. As the water-absorbing polymer, for example, one or more polymers selected from the group consisting of poly (meth) acrylic acid and alkali metal salts of poly (meth) acrylic acid, or the above polymer is subjected to a crosslinking reaction to water A polymer insolubilized in this manner can be preferably used. In the present specification, “(meth) acryl” means “acryl” and / or “methacryl” (one or both of “acryl” and “methacryl”). The weight average molecular weight of the polymer is not particularly limited, and examples thereof include those having a molecular weight of 200 to 100 million. However, a highly water-absorbent resin is preferably 10 million or more. As a polymer product form, powdered or granular products are sold. More specifically, CP-1 (model number) manufactured by Chemical Technos Co., Ltd. can be used as the powdery or granular superabsorbent polymer.

〔particle〕
The particles can be formed by absorbing water in a water-absorbing polymer powder. Although the amount of water absorption is not particularly limited, it is preferably 10 to 1000 times, more preferably 50 to 300 times the weight of the water absorbing polymer. By adjusting the amount of water absorption in accordance with the hardness of the model tumor, the properties can be more similar to those of each tumor.
The shape and size of the particles are not particularly limited. The shape of the particles is preferably a substantially spherical shape. This is because the particles are brought close to the shape of the cell, and the properties of the tumor model are similar to those of an actual tumor. The size of the particles is preferably 0.1 to 100 μm, more preferably 1 to 50 μm, and particularly preferably 1 to 5 μm.
In order to obtain such a particle size, a method of appropriately pulverizing a water-absorbing polymer powder is employed. Moreover, in order to arrange | equalize a particle size, it can be sieved using a cell strainer etc. By making the particle size uniform, it can be more similar to a tumor.

[Binder]
The binder in the present invention is a binder containing water. The binding material is not particularly limited as long as a plurality of particles can be bound to each other. The binder preferably contains a polyvinyl alcohol resin, borax, and water.
As long as the polyvinyl alcohol-based resin can be dissolved in water to form an aqueous solution, the degree of polymerization, the degree of saponification, and the like are not particularly limited. As the polyvinyl alcohol resin, those having different degrees of polymerization, those having different saponification degrees, those not copolymerized and modified, those copolymerized and modified can be used. Different types of polyvinyl alcohol resins can be used. Two or more kinds may be blended and used.

  The polyvinyl alcohol-based resin is obtained by polymerizing an aliphatic vinyl ester by a known method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization, and then saponifying. Saponification can be performed, for example, in a mixed solvent of alcohols such as methanol, esters such as methyl acetate and ethyl acetate, and alcohols. For the saponification, a method of using an alkali metal hydroxide such as sodium hydroxide or an alcoholate such as sodium methylate as a saponification catalyst is suitably employed.

  Examples of the aliphatic vinyl esters include vinyl acetate, vinyl formate, vinyl propionate, and vinyl pivalate. Further, an unsaturated monomer copolymerizable with an aliphatic vinyl ester and an aliphatic vinyl ester may be copolymerized. Examples of the unsaturated monomer copolymerizable with an aliphatic vinyl ester include α-olefins such as ethylene and propylene, unsaturated monobasic acids such as crotonic acid and acrylic acid, or salts thereof, maleic acid, and itaconic acid. , Unsaturated dibasic acids such as fumaric acid or salts thereof, or unsaturated dibasic monoalkyl esters such as monomethyl maleate and monomethyl itaconate, (meth) acrylic esters, acrylamide, dimethylacrylamide, N-methylol Amide group-containing monomers such as acrylamide and N-vinyl-2-pyrrolidone, alkyl vinyl ethers such as lauryl vinyl ether and stearyl vinyl ether, silyl group-containing monomers such as trimethoxyvinyl silane, allyl alcohol, dimethylallyl alcohol, isopropenyl allyl Alcohol etc. Hydroxyl group-containing monomers, acetyl group-containing monomers such as allyl acetate, dimethyl allyl acetate, isopropenyl allyl acetate, vinyl sulfonate group-containing monomers such as sodium vinyl sulfonate and sodium acrylamide-2-methylpropane sulfonate And halogen-containing monomers such as vinyl chloride and vinylidene chloride, and aromatic monomers such as styrene, but are not limited thereto.

When the binder contains polyvinyl alcohol-based resin, borax, and water, the polyvinyl alcohol-based resin is a polyvinyl alcohol-based resin solution, and borax is a borax liquid. It is preferable to prepare a binder.
The concentration of the aqueous solution of the polyvinyl alcohol resin in this case is not particularly limited. Preferably it is 1-20 mass%, More preferably, it is 5-10 mass%.
Although the density | concentration of a borax liquid is not specifically limited, A saturated borax liquid is preferable from a viewpoint of handleability.

Hereinafter, preferable numerical ranges for various values will be exemplified, but these numerical ranges are preferable from the viewpoint of providing a tumor model having characteristics similar to those of an actual tumor.
The binder is preferably mixed at the following ratio. That is, the mixing ratio of water (A), polyvinyl alcohol-based resin aqueous solution (B), and saturated borax liquid (C) is A: B: C = 0.1: 1: 0. 2 to 30: 1: 40 is preferable, 0.5: 1: 1 to 6: 1: 8 is more preferable, and 1: 1: 2 to 3: 1: 4 is particularly preferable.

The content of the polyvinyl alcohol resin in the binder is not particularly limited. The content of the polyvinyl alcohol-based resin is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 3.2 parts by mass, and particularly preferably 1 to 100 parts by mass of the binder. 2 parts by mass.
Moreover, content of the borax in a binder is not specifically limited. The content of borax with respect to 100 parts by mass of the binder is preferably 1 to 10 parts by mass, more preferably 3.2 to 4.3 parts by mass, and particularly preferably 3.8 to 4. 2 parts by mass.
When the content of the polyvinyl alcohol-based resin and borax is within this range, a plurality of particles are easily combined to form an aggregate. In addition, although it is preferable that the remainder of a binder is water, other solvents, such as alcohol, may be mixed.

The ratio of the total mass (D) of the plurality of particles to the mass (E) of the binder is not particularly limited, but is preferably D: E = 1: 0.1 to 1:10 on a mass basis, The ratio is preferably 1: 0.5 to 1: 1.5, particularly preferably 1: 0.8 to 1: 1.2.
The ratio of the total mass (F) of the water-absorbing polymer contained in the plurality of particles and the mass (G) of the binder is not particularly limited, but F: G = 1: 10 to 1: on a mass basis. 300 is preferable, more preferably 1:50 to 1: 150, and particularly preferably 1:80 to 1: 120.

(Water-insoluble membrane)
The material which comprises a water-insoluble film | membrane is not specifically limited. As the material, rubber which is a polymer material can be preferably used.
As the rubber, either natural rubber or synthetic rubber can be used. These can be used alone or in combination of two or more.
Natural rubber is a rubbery polymer obtained from natural plants, and the shape, color tone, etc. are not particularly limited as long as it has a cis-1,4-polyisoprene structure in terms of chemical structure.
The synthetic rubber is not particularly limited, and a wide variety of materials can be used. Synthetic rubbers include, for example, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene propylene rubber, urethane rubber, silicone rubber, fluorine rubber, chlorosulfonated polyethylene, epichloro Examples thereof include hydrin rubber and polysulfide rubber.
As the rubber, thermoplastic elastomers such as polystyrene-based thermoplastic elastomers, polypropylene-based thermoplastic elastomers, polydiene-based thermoplastic elastomers, chlorine-based thermoplastic elastomers, and engineering plastics-based elastomers can also be used.

The thickness of the water-insoluble film is not particularly limited. The thickness of the water-insoluble film can be, for example, 20 to 1000 μm, preferably 30 to 700 μm, and more preferably 50 to 500 μm. Within this range, the tumor model tends to resemble the actual tumor.
The method for forming the water-insoluble film is not particularly limited. For example, a method of applying and drying a coating solution containing a component of a water-insoluble film can be used. Examples of the coating method include various methods such as a spray coating method, a dip coating method, and a spin coating method. The coating conditions can be appropriately adjusted in consideration of the concentration of the coating solution and the desired film thickness depending on the coating method.

  An organic solvent is preferably used for the coating solution. As an organic solvent, you may use any of a 1st type organic solvent, a 2nd type organic solvent, and a 3rd type organic solvent, and these can be used individually or in combination of 2 or more types. Examples of organic solvents include carbon tetrachloride, 1,2-dichloroethane, 1,2-dichloroethylene, 1,1,2,2-tetrachloroethane, trichloroethylene, carbon disulfide, acetone, isobutyl alcohol, isopropyl alcohol. , Isopentyl alcohol, ethyl ether, ethylene glycol monoethyl ether, cellosolve acetate, butyl cellosolve, methyl cellosolve, ortho-dichlorobenzene, xylene, cresol, chlorobenzene, isobutyl acetate, isopropyl acetate, isopentyl acetate, ethyl acetate, normal acetate Butyl, normal-propyl acetate, normal-pentyl acetate, methyl acetate, cyclohexanol, cyclohexanone, 1,4-dioxane, dichloromethane, N, N-dimethylformamide, styrene Tetrachloroethylene, tetrahydrofuran, 1,1,1-trichloroethane, toluene, normal hexane, 1-butanol, 2-butanol, methanol, methyl isobutyl ketone, methyl ethyl ketone, methyl cyclohexanol, methyl cyclohexanone, methyl normal butyl ketone, Examples include gasoline, coal tar naphtha, petroleum ether, petroleum naphtha, petroleum benzine, and turpentine.

[Water-soluble membrane]
A water-soluble film | membrane will not be specifically limited if it has a property melt | dissolved in water, A wide film | membrane is used. Preferred examples of the film material include starch, gelatin, and polysaccharides. These can be used alone or in combination of two or more. Examples of the polysaccharide include amylose, amylopectin, mannan, pullulan, guar gum, soybean polysaccharide, agar, cellulose, pectin, carrageenan, sodium alginate, arabinoxylan, and derivatives thereof.
Although the thickness of a water-soluble film | membrane is not specifically limited, For example, it can be set to 5-500 micrometers, Preferably it can be set to 10-300 micrometers, More preferably, it can be set to 20-80 micrometers.

[Hardness of tumor model contents]
The hardness of the tumor model is not particularly limited. 1-100 kN / m ² is preferred. A hardness within this range is suitable as a soft tumor model for surgical practice using a surgical instrument. Here, the hardness is measured by a mixture of particles and a binder excluding two types of water-insoluble and water-soluble films. Fill a 50 ml centrifuge tube with 30 ml of sample, set the penetration speed: 10 mm / second, the measurement time: 3 seconds, the measurement temperature: room temperature, and update the force at a renewal rate of 10 times per second with a digital force gauge manufactured by IMADA. The value was acquired and the peak value was extracted from a total of 30 times. This is measured 5 samples, the average value derived from it is shown.

[Production of tumor model]
The method for producing the tumor model is not particularly limited. For example, the following method is preferably employed.
First, as shown in FIG. 2, particles 3 containing a water-absorbing polymer are prepared. Next, as shown in FIG. 3, the particles 3 are mixed with the binder 5 to form an aggregate 7. Then, as shown in FIG. 4, the aggregate 7 is covered with a water-soluble film 13. Further, the outside of the water-soluble film 13 is covered with a water-insoluble film 9 (see FIG. 1). In the tumor model 1, the water-soluble film 13 in FIG. 4 is dissolved or swollen and changed to a structure 11 (see FIG. 1) derived from the water-soluble film.

More specifically, a tumor model can be produced by the following procedure.
(1) The water-absorbing polymer is crushed in a mortar and selected with a cell strainer (for example, 40 μm).
(2) Pure water (filtered water) is absorbed by the water-absorbing polymer particles (weight ratio of 100 to 500 times).
(3) Mix borax (borax) with pure water (filtered water) to prepare a saturated borax solution.
(4) Mix water and polyvinyl alcohol resin, and further mix with saturated borax liquid to obtain a binder.
(5) A soft tumor-like tissue is produced by mixing a binder and water-absorbing polymer particles that have absorbed pure water.
(6) The soft tumor-like tissue is divided into a predetermined size (for example, 3 mm to 20 mm) and wrapped with an oblate.
(7) Further, a rubber is applied by spraying to form an outer membrane and dried.

[Effect of tumor model of this embodiment]
The tumor model according to this embodiment is similar in characteristics to an actual tumor. Therefore, it is useful for surgery simulation and the like. In addition, by adjusting the shape, size, binder, etc. of the particles, a tumor model similar to tumors having various properties can be obtained. Furthermore, since the aggregate is surrounded by a water-insoluble film, it is easy to handle.

  Hereinafter, the present invention will be described more specifically with reference to examples. Hereinafter, unless otherwise specified, ratios are expressed as mass-based ratios.

1. Formation of a preliminary tumor model In the following experimental examples, the following raw materials were used.
<Water-absorbing polymer (water-absorbing polymer)>
Product name: Super absorbent resin Model: CP-1
Manufacturer: Chemical Technos

<Oblate for inner membrane>
Product name: Round oblate Ingredients: Potato starch Manufacturer: Yodogawa Oblate

<Rubber spray for outer membrane>
Product name: Oil-based rubber spray Manufacturer: DSM Co., Ltd.

<Bo sand for adhesive binders>
Product name: Borax Composition: Borax (Na ₂ B ₄ O ₇ · 10H ₂ O) 99.0-103.0% Manufacturer: Kenei Pharmaceutical Co., Ltd.

<Polyvinyl alcohol (PVA solution) for adhesive binder>
Product name: Liquid paste paste Composition: Polyvinyl alcohol 8%
Manufacturer: Daiichi Soap Co., Ltd.

(Experimental example 1)
The water in the following ratio, that is, water-absorbing polymer particles was absorbed 100 times its own weight. There was no adhesion between the particles.

Water-absorbing polymer: water = 1: 100

(Experimental example 2)
The borax solution was added to the PVA solution at the following ratio. A sample similar to Mattel's toy slime was formed.

Water: PVA solution: Saturated borax solution = 1: 1: 2

(Experimental example 3)
A model was formed with the following ratios: The PVA solution and borax solution were added directly to the water-absorbing polymer in the dry state. It took time for the water-absorbing polymer to absorb water.

Water-absorbing polymer: (water: PVA solution: saturated borax solution)
= 1: (25:25:50)

(Experimental example 4)
A model was formed with the following ratios: The water-absorbing polymer particles were preliminarily absorbed. The PVA solution and borax solution were added to the water-absorbing polymer particles after water absorption.

(Water-absorbing polymer: water): (water: PVA solution: saturated borax solution)
= (1: 100) :( 25:25:50)

(Experimental example 5)
A model was formed with the following ratios: The water-absorbing polymer particles were preliminarily absorbed. The PVA solution and borax solution were added to the water-absorbing polymer particles after water absorption. After mixing, excess liquid was removed with a cell strainer.

(Water-absorbing polymer: water): (water: PVA solution: saturated borax solution)
= (1: 100) :( 37.5: 12.5: 50)

(Experimental example 6)
A model was formed with the following ratios: The water-absorbing polymer particles were preliminarily absorbed. The PVA solution and borax solution were added to the water-absorbing polymer particles after water absorption. After mixing, excess liquid was removed with a cell strainer.

(Water-absorbing polymer: water): (water: PVA solution: saturated borax solution)
= (1: 100) :( 33.3: 16.7: 50)

2. Evaluation of Preliminary Tumor Model In each experimental example, a 50 ml centrifuge tube was filled with 30 ml of a sample to form a tumor model having a cylindrical shape at the top and a conical shape at the bottom. The penetration speed: 10 mm / sec, measurement time: 3 seconds, measurement temperature: room temperature, and the hardness of the tumor model was acquired at a rate of 10 updates per second using a digital force gauge manufactured by IMADA. The peak value was extracted from a total of 30 times. Five samples were measured, and an average value was derived therefrom. Moreover, stress was applied to each tumor model and the state was observed. Furthermore, a sensory test was performed on the tumor model of Experimental Example 3 using an actual surgical instrument.

2.1 Hardness of contents of tumor model (hardness of preliminary tumor model, etc.)
(Experimental example 1)
The hardness was 4.18 ± 0.39 kN / m ² . The water-absorbing polymer particles were not adhered to each other. When stress was applied to the tumor model, it deformed and did not return to its original state. When the tumor model was pushed to make a hole, it remained in that state and the deformation remained. This tumor model was hard because of the high density of water-absorbing polymer particles, and was not similar to the tumor.

(Experimental example 2)
The hardness was 0.57 ± 0.19 kN / m ² and was soft and highly viscous. The tumor model became lumpy and hard immediately after mixing, but became uniform and soft over time. The tumor model was highly viscous. This tumor model was dissimilar to the tumor.

(Experimental example 3)
The hardness was 7.24 ± 2.48 kN / m ² . The water-absorbing polymer particles were adhered to each other. The tumor model was adhesive enough to be torn off by hand. In order to absorb moisture from the water-absorbing polymer adhesive binder, there was a large variation in hardness between manufactured samples. Over time, water was absorbed into the water-absorbing polymer, and the water-absorbing polymer particles were homogenized. This tumor model was similar to the tumor.

(Experimental example 4)
The hardness was 0.41 ± 0.19 kN / m ² . Since the water-absorbing polymer particles were preliminarily absorbed, each particle of the water-absorbing polymer had the same size. Since the binder entered between the water-absorbing polymer particles, the water-absorbing polymer particles were not denser than in Experimental Example 1, and were softer. This tumor model was similar to the tumor.

(Experimental example 5)
The hardness was 0.85 ± 0.10 kN / m ² . Since the amount of water was higher than in Experimental Example 4, it was soft during mixing, but the measured value of hardness after removing excess liquid was larger than in Experimental Example 4. This tumor model was similar to the tumor.

(Experimental example 6)
The hardness was 0.93 ± 0.08 kN / m ² . Since the amount of water was lower than in Experimental Example 5, the measured value of hardness after removing excess liquid was slightly larger than in Experimental Example 4. This tumor model was similar to the tumor.

2.2 Sensory test using surgical instrument A sensory test was performed on the tumor model of Experimental Example 3 using an actual surgical instrument. The feel of cutting this tumor model was found to be similar to meningioma.

3. Formation of Tumor Model Preliminarily prepared tumor models of Experimental Example 5 and Experimental Example 6 were divided into predetermined sizes (3 mm to 20 mm) and wrapped with an oblate of the same size. Further, rubber was applied by spraying to produce an outer membrane and dried. The tumor model of the example produced in this way was similar in characteristics to the tumor, similar to the tumor models of Experimental Example 5 and Experimental Example 6. In addition, the outer membrane facilitated handling of the tumor model.
In addition, drying experiments were performed on a tumor model covered (coated) with two layers of membranes (a water-insoluble outer membrane and a water-soluble inner membrane) and an uncoated tumor model. When each tumor model was manufactured and allowed to stand at room temperature, as shown in FIG. 5, many uncoated tumor models after 7 days contracted, but the tumor model covered with the outer membrane maintained its shape. It is thought that drying is prevented. Thus, the outer membrane suppressed the drying of the tumor model and was excellent in storage stability. The tumor model of Experimental Example 6 was subjected to a sensory test using an actual surgical instrument, and a questionnaire was given to three doctors. The results are shown in FIGS. The evaluation has five levels for each item, and a larger number indicates a better evaluation. As a result of the questionnaire, the tumor model of the present example was similar to the tumor and had a very high evaluation.

4). Effect of Example The tumor model according to this example is similar in characteristics to an actual tumor. Therefore, it is very useful for practice of surgery using an actual surgical instrument. Further, the outer membrane suppressed the drying of the tumor model and was excellent in storage stability.

  The present invention is not limited to the embodiments described in detail above, and various modifications or changes can be made within the scope of the claims of the present invention.

  The tumor model according to the present invention is similar in characteristics to an actual tumor. Therefore, it is useful for surgery simulation and the like.

Claims (4)

  A tumor model in which a plurality of particles containing a water-absorbing polymer are combined with a water-containing binder to form an aggregate, and the aggregate is surrounded by a water-insoluble film.   The tumor model according to claim 1, wherein a structure derived from a water-soluble film is present at an outer edge portion of the aggregate.   The tumor model according to claim 1 or 2, wherein the water-absorbing polymer has a structure derived from poly (meth) acrylic acid and / or an alkali metal salt of poly (meth) acrylic acid.   The tumor model according to any one of claims 1 to 3, wherein the binder contains a polyvinyl alcohol-based resin, borax, and water.